There is really not a great difference between land-based slots and online slots. This is because they now both rely on digital computer chip technology to generate their reels and slots, and the outcomes of spinning a reel. In earlier times, slot machines had an actual handle that you pulled to manually spin the reels. These days, while slot machines may still provide a handle for the sake of nostalgia, the inner workings of the slot machine are computer-based. In many cases the handle has also been replaced by a button that you press to start the reels spinning.
Some land-based slot machines have actual spinning slot online reels that spin inside the machine and stop at a certain point, much like a roulette wheel. However, there are increasing numbers of land-based slot machines that have a digital interface, meaning that the reels are represented virtually, in the same way as they are on your computer screen when you play online.
Thus the main difference between land-based slots and online slot machines is the way you interact with them. You physically take some action with a land-based machine, such as pulling a handle or pushing a button. Online everything is accomplished by clicking your mouse button.
There is one other area – which will be of great interest to you – where there is a subtle but important difference between online slot machines and ones in land-based casinos. This is that the payout percentage at online casinos is often higher than at real-world ones. This means that the casino’s “hold” or it’s advantage over you is slightly less, making your time spent online more profitable over time.