L Carnitine vs L Carnitine Tartarate?

Do l carnitine and l carnitine tartarate both increase androgen receptors? In the studies they have used tartarate, does it mean that only tartarate increases androgen receptors or even normal l carnitine does the same?

The only difference the tartrate makes is that L-carnitine without the tartrate is quite hygroscopic (absorbs water.) Using the L-tartrate form makes a product more stable to moisture exposure. There is no difference in the body.

What about acetyl L carnitine? What’s the difference between the 3? Which is best?