That was my initial reaction upon reading the thread, but I was shocked to read above that they average the same in one-day cricket. Jayasuriya is a real legend of ODI cricket, whereas Sehwag is generally considered to be a surprising failure in the format.
This is a good example of why looking at overall career averages - particularly in ODIs - can be misleading.
Firstly, Jayasuriya was picked as an allrounder in ODIs a little while before he was ready to play as a specialist batsman. After 70 ODIs - mostly as a lower middle order batsman anywhere from 5 to 8 - he averaged only
15.18. In his 71st ODI he scored his first ODI hundred and it was only then he started opening on a permanent basis. Since such a time where he justified selection on his batting alone, he's averaged 35.96 at a SR or 93.26 - figures that resemble that of Adam Gilchrist much more than they do Sehwag.
Secondly, Jayasuriya played a fair bit of his career in an era where the expectations of batsmen were a bit different... to plug my own article,
it's shown here in the global batting averages and strike rates table. He was in fact one of reasons this changed when it did - a lot of his legacy is based on the fact that he was a man slightly before his time - at least before he made his time become his own.
I don't really put him in the absolute elite class of ODI batsmen that some like to, but he wasn't too far aware from it, IMO. He's certainly a fair bit better than his overall stats suggest if you're comparing him to players with relatively younger careers.. indeed like Sehwag.
I said "Sehwag by a long way" or something similar in my first post on this matter, but that was obviously because I was going by the unwritten "assume Tests unless it is specifically stated otherwise" rule of CW. In ODIs it's Jayasuriya by a similar margin to what it is for Sehwag in Tests.