Anyone switching from live cash games to online cash games is going to notice differences. The most drastic difference is the large in Pre Flop strategy. Players who are comfortable with the aggressive nature of online cash games tend to over play their hands Pre Flop in live cash.
Online, it is almost never correct to limp in a cash game. There are certain exceptions. Say, for instance you are at a table and several persons, yourself included, are 150 Big Blinds deep. If someone limps, and another persons limps, it might make sense in this situation to limp. But when playing normal 100 Big Blind poker it is almost never correct to limp.
In a live game however, you will often limp. The reason is twofold. First, you see far fewer hands per hour and people simply won't fold Pre Flop. They want to see the flop and a raise is going to be called by several players.
This does not mean that live you should never raise. If you have a strong hand such as Aces, or any high pocket pair, or are on the button with suited broadways, then you should raise because you have position and a strong holding. But the concept of iso-raising that is found in online poker simply is not as prevalent live.
Online, if you have position on a weak player it is correct to iso-raise them with a wide range of hands. This will lead to a profit long term. They will check fold most flops they miss. However, if you attempt to iso-raise live, you will be losing money. You will not find that many people will fold even if they are out of position.
The second big difference is that there are going to be many more multiway pots. This follows because so many people refuse to fold for a single raise. Therefore hand strength changes. With 5 people or more in a pot, you need to take into consideration a wider holding. Online, it will usually be three or two persons to the flop, and almost always two to the turn.
The general rule is that live play is much weaker than online. This is because there are far more recreational players live than online. They may have little experience playing poker and therefore are not familiar with simple concepts such as position, pot odds, etc...
While they play is slower, it is also more profitable for those who do not like to multitable. If you are someone who is not comfortable playing multiple tables online, then your win rate playing poker is going to be much higher live. The reason players play online is that besides the convenience of being able to play when and where they want, they can also play a dozen tables if they choose and maximize their hourly.
Even though live you can only play one table, the competition is so soft that your bb/100 at a live table is going to much higher than online. Strategy wise, there are also advantages.
You have much more information. While you don't have access to a HUD or PokerTracker, you have the person right in front of you. You can see them bluff, or if they are weak passive. This helps you with important reads. So that for instance, you get to the river and have top pair and bet three quarters pot. If a weak passive type check raises you big, you can be sure you are not good. This information can be used in lieu of any of the tracking software that is incapable of being used live