@elbanditoroso You may be describing the difference between what’s commonly called “dark” (velarized) /l/ vs. “light” (non-velarized) /l/. “Velarized” means that the “l” sound is pronounced with the back of the tongue up toward the velum (back of the mouth). In English, this sound is most noticeable at the end of a word (which is often spelled “ll”) as in ball, fall, fell, hull, etc. But in American English, “l” is often velarized to some degree, just more so at the end of a word or preceding a consonant (as in the word “film”). (Cf. Spanish, where the “l” is never velarized or Russian where it is strongly velarized at the beginning of a word, unlike English).