Whilst the rules of the game may remain the same for whatever your flavour of poker, there are a few marked differences that are worth noting when it comes to online vs live poker.
The Way You Play
Live poker is very much about interacting with your fellow players, watching for their tells, betting around their play styles. Online poker lacks this, so adjust your play style accordingly.
Online gives you the opportunity to be playing multiple tables at once. This means you can spread your games amongst a number of smaller pots rather than putting everything into one big game.
This is personal but I think it applies, I’ve always found the attitude of live players much more appealing. As with everything online the veil of anonymity that the internet gives means people can be very rude or unprofessional in online games. There’s usually a mute button though so don’t let it distract you.