What is the difference between filter coffee and plunger coffee?

Filter coffee is coffee brewed through a filter. It has less oils and the grounds don't get in the coffee. The main filter coffee brewing methods are:

Regular Drip Coffee (which is your standard/typical coffee machine on your kitchen counter)

Pour Over (It's a manual way of doing drip coffee, no machine, just a filter and a cup)

Chemex (which is pretty much a pour over but a little different)

and there are many more.

A plunger coffee... is a press. The press is called a plunger. The french press is another way to brew coffee.

First you have the grounds, then you add in boiling or a little under boiling water, then you let it brew for 4 minutes, then you add the plunger/ press, and press the grounds to the bottom of the pitcher. This gets most of the grounds to the bottom of the pitcher and leaves you with the brewed coffee.

This way leaves you more oils than the filtered coffee. Some people enjoy the oils and some people don't.

That's the different.

Google "French Press"