ST has something like 24 planetary classifications. Here's what I think of when I compare them to Traveller:
A,B,C: Sizes 1-4.
D: Size 0.
E,F,G: Sizes 6-8.
H: Desert worlds.
T,S,I,J: Gas giants, largest to smallest I guess.
K: Size 6-8, Atm 1-3.
L: Size 6-8 with a marginally breathable atmosphere.
M: Terran norm.
N,X,Y,Z: Atm 11 or 12 Hellworld.
O: Water world
P: Tundric water world.
Q: Elliptical atmosphere or other strangeness.
R: no analogue in Traveller for explicitly coding a Rogue world. Might be nice to have that though!
A,B,C: Sizes 1-4.
D: Size 0.
E,F,G: Sizes 6-8.
H: Desert worlds.
T,S,I,J: Gas giants, largest to smallest I guess.
K: Size 6-8, Atm 1-3.
L: Size 6-8 with a marginally breathable atmosphere.
M: Terran norm.
N,X,Y,Z: Atm 11 or 12 Hellworld.
O: Water world
P: Tundric water world.
Q: Elliptical atmosphere or other strangeness.
R: no analogue in Traveller for explicitly coding a Rogue world. Might be nice to have that though!