I would never expect powder when I said MDMA, I would expect crystals or pills. Ecstasy is often said to be cut with other substances, but almost never is, because most other drugs are more expensive and less potent than MDMA. There are often impure batches containing meth or other amphetamines, often other "designer drugs" being pressed into pills and sold as ecstasy while not being MDMA, but rarely intentionally cutting the MDMA with other drugs.

Drug pro-tip: anything powder is garbage, crack comes in rocks (crack users aren't all that picky though, from beeswax to swiss cheese to chalk, from white as snow to bright yellow, usually off-white, it comes in a variety of appearances and textures and users savor the cut - the most favored stuff is usually not the purest), coke comes in chunks (white, off-white, even yellowish, good quality stuff has a flaky structure and pearlescent shine), heroin comes in chunks (from white to tan to black, occasionally gooey), weed comes in nuggets (but used to come in chunks, maybe still does if reggies/illegal weed still exists in your area), meth is long usually clear crystals, molly is shorter and more cuboid crystals, usually colored (pink, tan/brown, only very rarely clear).

You are right, I used the wrong wording here. I meant crystals, not powder. I used the word 'powder' unconsciously because when I was raving, I would break those crystals into powder form to control the dosage better.

Anyway, regarding the difference between ecstasy and MDMA, from personal experience, I cannot remember a time when the effects were the same. Every time I took a pill, the effect was totally different from MDMA. MDMA provided a more 'pure' experience, whereas with advertised 'ecstasy' pills, I experienced hallucinations, memory loss, and a very heavy hangover.

2CB, MMC3/4, synthetic Psylobin and others are fine in powder form