Both combinations of hands have the same length for each type of hand. The hour hand extends nearly to the inside end of the hour mark, with a slight gap. The minute hand will extend all the way to between the end of the 1/5 second marks and the second/minute marks. The chronograph second hand tip extends all the way to the 1/5 second marks, the tail should not extend into the registers (hand should end at COMPAX when is at 0).
Early hands: seen up to 2.5 serials
The first set of main hands were silver, with lume, for both the hour and minute, and a blued chrono seconds hand, also with lume. These hands were used on the early Nina “Mk 1” dials.
Later hands: seen from 2.5 serials and on
Later hands were all black with lume, including hour, minute and chrono seconds. These were used exclusively on the later Nina dials.
I have seen two examples of watches with non-luminous chronograph seconds hand, both existing on pieces with pulsations bezels. The reference 885105/02 of these two has the highest serial of any Nina I have seen, so the possibility exists that Universal Geneve simply depleted the supply of luminous chronograph seconds hands and used a non-luminous hand.
Universal Geneve has stated that “885105/02 with a black pulse-counting bezel has been produced only with ‘Bâton’ hands with central fissure for tritium for registers, hour, minute and center chronograph.” As reference, the company has stated that the 885108 also “has been produced only with ‘Bâton’ hands with central fissure for tritium for registers, hour, minute and center chronograph.” 
 Universal Geneve, email May 5, 2020