Havent played the remake yet.... is THAT much different from the original?
Quite a bit. Even taken by itself, the game has some weird continuity issues between the two routes that weren't present in the original. Such as Leon and Claire fighting the exact same bosses in the exact same rooms and Annette getting fatally injured twice after having (roughly) the same conversation with both Leon and Claire.
Some aspects of the story were changed as well such as the new addition of an orphanage level whose overall concept was scrapped in favor of a Sherry stealth section. Mr. X or Tyrant now show up in both character's scenarios with two possible ways it can die (effectively tying into the continuity errors mentioned above) which has led fans into believing that there are now two of them at least.
Chief Iron's physical depiction and personality are quite different from the original. For better or worse is down to individual preference.
And as mentioned in previous posts, Ada's portrayal and cover story were changed. And the Kendo Gunshop owner is a completely different character now.
Ben the reporter also seems like a different person now and his cause of death was also changed, but overall his role remains pretty much the same.
Some enemies were either cut entirely or changed.
...I could probably write out a long list of other changes, but I'd be here all day.