Online casinos have become the new way to play recently, so taking a look at how the game may have changed to accommodate it's new environment seems like it could be a good idea.
In the old days to find a countable game in a casino was easy, but today... they do their best to prevent counters to use this system of counting cards and to to that they play with more decks and cards are often reshuffled after every hand . On the online games is the same thing you have no chance if you are a counter, because the cards are reshuffled constantly. Card counting is a strategy that died with the reshuffle, as it depends wholly on the deck being dealt down a significant degree.
So now, you will ask me whats the difference than between playing online or in a land based casino. The strategies you play with are the same, but the difference is your surrounding environment. All of the distractions Vegas casinos throw at you (and there's certainly no shortage of them) disappear. This advantage stretches to other more defined areas too, which I feel are worthy of note. Playing blackjack at the casino requires you keep up to the pace of the table your at, while playing online blackjack lets you set your own pace.
Besides, when it comes to strategy, time is in your hand, and that's what online blackjack offers above and beyond the casino. You can easily print up a basic strategy chart for the game you're playing and reference it for as long as you like, as many times as you like. You can make bets that you might not make in front of other people at the casino.