There are going to be two versions:
- A Commander-level (Tier 3) one available for energy credits or ship tokens.
It's the regular Excelsior-class, as seen in ST VI and TNG/DS9 (although, strangely, it's being advertised as the 'ST III' version - clearly the bods at Cryptic aren't aware that the 'Search for Spock' Excelsior and the 'Undiscovered Country' Excelsior aren't exactly the same...).
- A Vice Admiral-level (Tier 5) one available for retrofit tokens, emblems (?) or through the C-Store.
This is the Excelsior variant (Enterprise-B/Lakota) shown above, although it'll be possible to choose the regular Excelsior hull components as well, with the option to 'mix and match' (i.e. 'kitbash'...). It's being marketed as the 'Lakota' version - why they can't just call it the 'Excelsior Variant' is beyond me, but then again, the original Constitution class is referred to as the 'TOS USS Enterprise' in the C-Store, which is equally facepalm-worthy.
The Commander level Excelsior is the STIII: TSFS variant. the VA1 version refit (coining later) will be the U.S.S. Lakota (from DS9 - 'Paradise Lost'/Star Trek: Generations
As for the original 1701 being advertised as the 'TOS Enterprise' instead of 'Constitution Class' - realize that DURING TOS the 1701 was refered to as a 'Starship Class' vessel. The 'Constitution Class' designation was n't introduced until the Franz Joseph 'Star Trek Technical Manual' circa. 1975 - and wasn't stated on screen UNTIL ST:TMP. So, if anything, Cryptic's description is probably more acurate - considering the ST:TMP Constitution Class Enterprise is also in the game as a 'free' Lt. Cmdr. level ship.