T-80U and T-80B
The forum quoted documents that clearly mentioned the T-80 Burlak and T-90 Burlak. I found the Object 640 mentioned in your link, but I'm not sure what relevance that has.
That is what I'm trying to say. That site has good reputation for not jumping to conclusions, unlike forums. It only says Т-80У
/Б «Бурлак» to be modernised at Omsk, not a "T-80UB"
and the T-90s to be modernised. T-80U and T-80B are 25 year old production models, including those made in Kirov plant, that are probably only now getting deep upgrades, and are probably coming from storage bases, having entered conservation in the early 1990s.
Probably T-80Us will get priority since the financial crisis is making defence budgets very unstable all over the world.
Given discussion on the forum, and that Burlak involves serious pulling, I can only suggest that there may be internal turret upgrades (that required 'pulling' money from budget), but also possibly, and only possibly, external armour upgrades that would require some powerplant modernisation also.
Burlak is a really strange name to give to a tank project in Russian, and it is already used for an air force engine and an AA missile I think, to I'm just reading between the lines and into semantics of the name for now.