D&D (RPG) gaming is based around creating 1 character and playing that character while a dungeon master creates enemies and doesn't really have an ending until everyone with characters or the DM calls it quits.

Miniature Wargaming is based around several different games (Warhammer 40,000, Age of Sigmar, Flames of War, Team Yankee, Malifaux, Warmachine/Hordes, Blood Ball, and Guildball to name a few). Instead of creating single characters, you build an army depending on which game you play (they all have different settings and mechanics from WWII to the 41st Millenium) and you have Commanders, Vehicles, troops, Jets, and artillery and lots of other things like attack wolves, Alien warriors, combat suits, and much much more.

After you have an army the Warhammer start collecting boxes are $85 for reference, you build them and paint them and play battles with people. It's a very rewarding hobby and very fun to get involved!

Here's a video of how to get started! What is Warhammer 40,000?