Boxing or Muay Thai: where should I start?

Start with the hands. It does not matter which one you are aiming at.

Boxing is hands only: jab, cross, hook, uppercut, plus the footwork and head movement that make any of it land. Muay Thai is the art of eight limbs, so kicks, knees, elbows and clinch work go on top. But your stance, your balance and your guard all come out of boxing, and everything else gets bolted onto that frame. Somebody who kicks beautifully but stands wrong gets hit on the way in. So your first few weeks look identical either way. Stance, jab, cross, move your feet, chin down.

After that they do feel different. Boxing is tight and technical, a lot of range and a lot of upper body movement, because hands are the only thing coming. Muay Thai stands taller and heavier, because you cannot be lunging around on a lead leg somebody is about to kick, and the clinch changes how you hold yourself entirely.

For self-defense, learn both and lean on the hands. For fitness, pick the one you will actually show up for, and read training striking purely for fitness. For MMA you need Thai kicks and the clinch, because that is where wrestling and striking meet.

Whichever way you go, the first punch is the same one and it is not the exciting one. Why everything starts with the jab explains why your first hour goes on a shot that does not look like much.

If you are leaning Thai, the kicks show up sooner than people expect and take longer to own than they hope: how long before you can kick properly.

And the thing that genuinely separates the two is what happens when you run out of room. Boxing has very little there. Muay Thai has an entire game. What the clinch is covers the range where most real fights actually get settled.

I have been teaching boxing, Muay Thai and kickboxing since 2008, and I still hold the pads myself, so you get the correction in the middle of the round instead of a lecture after it. See what you can train.