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?

1xbet is legal in many countries in Europe, South America, Asia, Africa, Oceania. However it is not legal in some notable countries like USA, UK.