Su-25T (Su-25TM Tankovyi Modifitsirovannyi, Antitank) -- Proposed enhanced version with more armor, improved sensors, and possibly a new gun and engines [Su-25T's production designation is Su-39, up to 22 built.]
Su-25TK -- Proposed export version of Su-25T tank-buster
Su-25TM ("Su-39" strike shield): Improved all-weather multirole export version variant, three built.
Su-25SM: Russian Air Force single-seater upgrade with improved avionics, program in progress at last notice.
Su-25KM Scorpion: TAM/Elbit upgrade demonstrator, one update from older single-seater.
Su-25SM - A Su-25 upgrade. The Su-25SM may be the most effective means to support the Syrian government forces in the fight against the group "Islamic State", just as the US used the A-10 attack aircraft to support the Iraqi authorities.
Su-25 two-seat variants
Su-25U -- combat trainer
Su-25UB (Frogfoot B) (UB - Uchebno-Boevoi, Combat Trainer) -- Two-seat combat trainer, possibly 130 to 180 built.
Su-25UBK -- Export version of Su-25UB, possibly 20 built.
Su-25UBP -- Naval trainer based on Su-25UB
Su-25UT (Frogfoot B) (UT - Uchebno-Trenirovochnyi, Trainer) -- Unarmed primary trainer (sometimes referred to as Su-28). Proposed DOSAAF trainer, one conversion from Su-24UB.
Su-25UTG (Frogfoot B) (UTG - Uchebno-Trenirovochnyi Gakovyi, Trainer Naval) -- Naval trainer based on Su-25UT, with ruggedized landing gear and arresting hook. Ten built.
Su-25UBP: Su-25UTG with inflight refueling probe, ten to be built as conversions of Su-25UBs, unclear if any were.
Su-25UBM: Russian Air Force two-seater upgrade with improved avionics, program in progress.