Let's look at some specs.
Size:
Galaxy Class Starships are 641 meters long.
Emperor Class Battleships are at least 3km long.
Armament:
Galaxy Class Starships have at least 10 Phaser arrays, and over 200 Photon Torpedoes (6ft long, max range 750,000-3,500,000km depending on type).
Emperor Class Battleships have hundreds of Plasma Cannons, Turbo Lasers, Defence Lasers, Macro Cannons and simmilar weaponry, Lance Batteries, auxilliary defence Turrets and an unknown quantity of Torpedoes (size and range unknown).
Auxilliary Craft:
Galaxy Class Starships have 10 standard personnel shuttles, ten cargo shuttles and 5 special-purpose craft, as well as 12 2-man short range craft.
Emperor Class Battleships have an unknown number of fighters, assault craft, bombers, planetary assault craft, dropships, drop-pods as well as an unknown quantity of additional craft.
Hope that helps you determine how Star Trek ships shape up in BFG.