Senna was the God of his era. You could argue that Schumacher was the God of his, love him or loth him. And the early Gods, Fangio and co, were Gods of their era.
I think the Schumacher return shows that these greats couldn't survive in a different era.
Senna would have eaten scumacher for breakfast in any situation. Apart from all his other attributes he had more intelligence in his little finger than Scummy has in his head.
He was also naturally gifted to an unbelievable degree, which Scummy isnt - which is why he has to cheat and bully at every single opportunity, to get his results.
I think his comeback has demonstrated that now that he has lost the influence to tip the scales in his favour - team orders, rules dont apply to him or his car etc. - we are seeing his level of real talent, which is somewhat mediocre.I think the difference this time around may well be that now that Ross Brawn is the team principal, he wont run a bent car, whereas Ferrari always ran a bent car in the Scumacher era, and the FIA turned a blind eye to it.
Did I mention before that I detest the bloke ? 
We will never know. Both, I feel, had a real feel for the cars and the grip available, and both had a real determination to win. At any cost. I'm sure Prost and Piquet would be equally as harsh at Senna as Hill was to Schumacher.
I was one of the Schumacher loathers in the Hill/Villeneuve era, but since missed his real, true desire to win, which is something missing from every single current F1 driver, including Webber (who used to have it), and Hamilton who showed initial promise.
Schumacher was the best of
his era imho, though not any other greats during that time, unlike Senna, who had Prost, Piquet, and the real mans man, Mansell (love or loath him)