A sequence is an ordered list of numbers, so position matters. Each number is a term, and the position tells you whether it is first, second, third, and so on.

A term-to-term rule tells you how to move from one term to the next, such as "add 4". An nth-term rule, such as $4n+1$, gives the term at position $n$ directly.

When you meet a new sequence, check the gaps between consecutive terms. Do not just use the first gap, because some sequences have changing gaps.