It will probably not come as a shock that SWTOR is sticking with the four core server rulesets: PvE, PvP, RP-PvE, and RP-PvP. In PvE, players have to toggle an option to engage in PvP outside of specifically designated combat areas, while on PvP servers everyone is automatically flagged outside of safe areas, such as the starting zones. The RP variants are similar, except that BioWare encourages players to roleplay in character on those servers. There's no word as to whether or not GMs will be enforcing such actions.
Because RP-PvP was a very recent addition to the server ruleset list, guilds participating in the pre-launch deployment program will not be able to choose those servers for launch. Instead, BioWare says that players interested in this ruleset will need to manually form a guild on their faction's homeworld after the game releases.