Do Russians differentiate between “I am going to do something.” and “I will do something.”? If yes, how?
A pre-meditated intent usually is indicated with a word like хотеть (to want) or собираться (to prepare for smth) with a verb in present or past tense (Я хотел/собирался перекусить - I wanted/was planning to grab a bite). If you come up with an idea on the spot, a verb in future tense is usually used (Пойду перекушу - I’ll go grab a bite)