If you consider live streaming to be actual live, real time, as it happens, then there aren't that many services available. But, if you consider a service that performs similar to traditional TV, then there are many. Let me offer a couple of examples of that varied difference.
Services that are intended to be and act like cable replacements fall under the category of live streaming. They are, as mentioned, replacements for cable TV and act pretty much like cable TV services. They also usually have a larger cost involved, although at this writing, the prices range from less than $20/month to around $80/month, with most in the $65/month range. Some of these include Sling TV, YouTube TV, Philo, Frndly TV, Vidgo, Hulu + Live TV, Fubo, AT&T TV, Univision Now, and more.
There is also another group of live streaming services that aren't generally thought of as cable replacements, but still are much like the other ones mentioned. These include Pluto TV, Tubi TV, Xumo, Stirr, and others.
The primary difference between these services are the selection of channels, but not necessarily the type of content. For example, Pluto TV -- I'm choosing this because it's the biggest of the similar services -- has a wide variety of movies and TV shows playing all day, much like the "superstations" of days past. You go to a particular channel and watch a movie. If the movie is already underway, you can watch it to conclusion, then watch whatever comes on next. This is similar to watching cable channels such as TCM in how it operates, and even with some of the content.
For Sling TV -- I'm choosing this service as it's the oldest of the major services -- you can go to TNT, History, AMC and the like, and watch it.
A main difference is that you won't find first-run content on Pluto TV like you will on Sling TV. But, if you enjoy reality TV, movies, classic TV shows or cartoons, news, and other content, you can find similar, but not the same, content on each service. One may be better, or newer, but the overall type of content is the same.
The other difference is price. Sling TV and the other services cost a monthly fee. Pluto TV and other similar services are free, ad-supported services. And, you will still see commercials on Sling TV just like you do on cable.
Which do you need? That's easy: which do you want?
You have options, plenty of options, to help you enjoy your Streaming Life.