There is no significant difference. Both sites are operated by the same company, 1xCorp N.V., or something like that. The only differences are in the frontend design and the fact that 1xbit does not have a license, so it operates illegally. Re: What is the Different Between 1XBet and 1XBit?
At 1xBet, TO 1 and TU 1 refer to Total Over 1 and Total Under 1 bet, respectively. These bets are placed on the total number of goals (in football), runs (in Cricket), points (in basketball), etc., scored in a game.