Comparison between the theatrical version (Blu-ray) and the Director's Cut (4K-UHD) - both included on Paramount's 4K/Blu-ray set.
Nicholas Meyer not only sat in the director's chair for Part 2, but was also allowed to take over this job in 1991 for Star Trek VI: The Undiscovered Country. In this case, however, the studio beat him to the punch, because Paramount had already released a version of the film on VHS and laserdisc in the 90s that was slightly longer than the theatrical version. The difference in running time is mainly due to two additional scenes, which somewhat deepen a few side characters. For the Special Edition DVD in 2004, Meyer added a few short re-cuts to this already extended version during the interrogation of Lt. Valeris to people she mentioned, which gives a few more characters brief screentime. So basically, with or without these cuts, it's mostly fan service. One can also be satisfied with the theatrical version.
In this case, by the way, the scenes were, unlike the predecessors, not seen in advance during the broadcast of the US channel ABC. But, apart from the cuts in the interrogation scene, the version here was, as said, already available before the DVD era anyway. In many countries, on the other hand, it was not that easy to see the original theatrical version. The Blu-ray release in 2009 was surprising in this respect, because it only contained said theatrical version, so that some fans criticized that the additional material of the previously expanded version was suddenly missing from the film.
After the first films already received their UHD premiere in 2021, it was finally time for Star Trek V: The Final Frontier and Part 6 in September 2022. The 4K Blu-ray now contained the extended version for the first time again, including interrogation recuts and in massively improved picture quality compared to the old Blu-ray. The version is called Director's Cut here, but it corresponds to the previous Special Edition DVD. In addition, the theatrical version is also included in 4K, so this release is clearly recommended to every fan. The included Blu-ray, however, is again only equipped with the theatrical version.
38:53 / 38:52-40:40
Kurtwood Smith (as President of the Federation) assures John Schuck (as Klingon Ambassador) he will show deference to the federation's laws. The Klingon's ambassador leaves the room! A voice over speaker announces the visit of the space fleet's command. Leon Russom (as Starfleet Commander in Chief), Brock Peters (as Admiral Cartwright) and Rene Auberjonois (connotation: this actor will later be known as popular character Odo in the Star Trek TV series DS9)(as Colonel West) enter the office. The president greets his guests and offers them to sit down, everybody except Colonel West do so.
Admiral Cartwright tells the president it could not be allowed that citizens of the federation are being abducted. The president replies that he must show deference to the laws. Then the spacefleet-commander's boss asks the president to apply his attention to Colonel West's presentation. He immediately starts his explanation of how to rescue Kirk and Dr. McCoy from the Klingon's hands. This, he does with an old-fashioned flip-chart and a laser pointer. The president interrupts by saying this would only lead to war. Col. West is aware of that and says the now weakened Klingon's had no chance anyways now. The president asks Romulan ambassador Darryl Henriques (as Ambassador Nanclus). He says this was a good time to go to war against the Klingons.
The president interrupts the conference by saying he will keep this plan in his mind. Everyone except Mark Lenard (as Ambassador Sarek) leaves the room, the last one of the spacefleet commander's boss' group tries to appeal to the president that the men had saved the earth several times, the president responds by saying they will again, in the court room.
107.7 sec (= 1:48 min)
41:27 / 43:13-44:34
After the sighting of the database, James Doohan (as Captain Montgomery Scott) assures Leonard Nimoy (as Captain Spock) once more, that no torpedo from the Enterprise's stock is missing. Spock says the computer was probably lying, Scott replies computers couldn't lie. Of course, Spock knows that. He orders Scott to count each and every torpedo. Scott says this would take hours whereas Spock answers this was the only way to prove the database has been manipulated and therefore, Kirk and McCoy are innocent.
Kim Cattrall (as Lieutenant Valeris) joins the two over a 'fire department pole'. (The actress is a little clumsy doing this and hits the prop walls and presses them in visibly. This may be a reason this scene wasn't included in the theatrical version.) Now, Lieutenant Valeris reports the Klingon-chancellor's daughter had something to do with her father's assassination and that she didn't shed a single tear. Very drily, Spock comments that Klingons don't have any tear glands.
80.3 sec (= 1:20 min)
79:06-79:10 resp. 79:15 / 82:13-82:16 resp. 82:21-82:25
In the Theatrical version Scott is seen in close-up at the conference table at the beginning of the scene. He grabs his neck here. This shot also appears in the Director's Cut 5 sec later, after the close-up of the plans on the table and before he stands up in distant view.
The Director's Cut instead has a first distant shot of Scott for starters. This shot remains exclusive.
Director's Cut 2.9 sec longer
83:25-83:28 / 86:35-86:39
At Kirk's words "my personal log was introduced as evidence against me", the Director's Cut changes to a close-up of Kirk. The theatrical version, meanwhile, remains in long shot.
Director's Cut 1 sec longer
83:53-83:56 / 87:04-87:07
Along with McCoy's "And what do you think you've been doing?" there is another close-up in the Director's Cut, while the theatrical version again shows the long shot.
No runtime difference
85:44-85:47 / 88:55-88:58
Spock makes a mind connection with Lieutenant Valeris. In the theatrical version, the camera only moves around the two of them in one long shot. In the Director's Edition, the camera fades to white and shows the traitors' pictures in addition to their names. This is emphasized by a short sound effect. Here Admiral Cartwright appears first.
No runtime difference
86:05-86:07 / 89:16-89:18
The next one mentioned is General Chang (Christopher Plummer).
No runtime difference
86:17-86:19 / 89:28-89:30
And Ambassador Nanclus.
No runtime difference
99:32 / 102:43-102:46
The dark red blood of the seemingly Klingon assassin is being noticed bewilderedly.
99:36 / 102:50-103:01
The spacefleed commando's boss and Michael Dorn (as Colonel Worf) reveal the assassin as Colonel West.
Finally, a small picture comparison. In this case, the DVD was set to the then "trendy" aspect ratio 2.00:1. The Blu-ray and 4K Blu-ray again use the original 2.35:1, so most scenes are somewhat matted (though without losing anything relevant). In some cases, especially during the additional close-ups towards the end, the old version was simply zoomed in.
Note, by the way, that because of the HDR->SDR conversion, the 4K screenshots here (and in the actual report above) look darker than they actually are on the disc.