I Imagine alot of what we see in films is just for show and to look good, so how does it compare to the real thing?
For the most part, they're (cinematic sword play) all for show and action. In real life, many of the techniques, methods, and movements used in TV and Cinema would result in said person being cut to bits by an actual trained fighter.
Here are some examples of swordplay/action critiques from various (by reputable) youtubers.
https://www.youtube.com/watch?v=PXbSv7lhKzg
https://www.youtube.com/watch?v=qFBK-eVl76M
In addition, here are examples of actual martial arts, specifically from the 15th century (So full plates of armor could be involved). As you can see from these sources, a fight could be over in a few seconds or in one, brief exchange of attacks and responses. Of course, this doesn't mean that an opponent is necessarily killed, but incapacitated and unable to fight.
Several years ago, a documentary was released that addresses this question. It's called Reclaiming the Blade. Schola Gladitoria (mentioned in other comments) is featured in the film. The film examines the stereotypes of swords and sword fighting that abound in film. It also shows how scholars and martial arts enthusiasts are "reclaiming" the European martial arts by studying and practicing the fighting techniques contained in medieval and Renaissance fighting manuals.
Edit to add: Here's an example from the film of fighting techniques featured in Renaissance training manuals being used to choreograph a stage fight
And if you're interested in looking at the training manuals themselves, check out ARMA.
How smart do you think it would be to spin around or draw your sword high above your head to slash an opponent? Any experienced fighter would simply poke you in the guts while your sword can't block theirs.