Yes, totally different pharmacokinesis. Weed is slow to break down, so it accumulates on the body. On the fat tissue and myelin of neurons. Long term use makes you get used to a base level amount of THC.

Alcohol is metabolized very fast by the liver, which can adapt to get more efficient by changing enzymatic production. But it also suffers tissue damage that is very hard to recover. With long term use, at one point the damage overruns adaptation. Then you lose your entire ability to tolerate alcohol. Which for alcoholics is harsh, since their dependency doesn’t go away.