please note this post makes reference to the October 29 episode on CBC
There's definitely a big difference between Nick Tilsey before the accident and Nick Tilsley after the accident. Once Nick woke up from his coma, he was a changed man (I guess attempted murder by your brother will do that to you - ed). It can be a bit confusing so here's a handy guide to help tell the difference.
Pre-coma Nick was cheerful
Post coma Nick is surly
Pre-coma Nick loved David
Post-coma Nick hates David
Pre-coma Nick would have been relieved to know he wasn't the father of baby Lily
Post-coma Nick seemed disappointed that he wasn't the father of baby Lily.
Pre-coma Nick liked Simon to chat
Post-coma Nick likes Simon to shut it
Pre-coma Nick thought Gail was a pain
Post-coma Nick thinks Gail is a pain
(Well, some things don't change).