їздили vs. ходили

[KTamaslingo]

Maybe I am missing something obvious but I don't quite get the difference. Sometimes they are interchangeable, sometimes they are not?

[tjomd]

I'm Russian but we do have these verbs, the first one [їздили] means moving by some kind of transport, the second [ходили] means moving by foot. Both are in the past tense and mean moving a lot of times in the past (not a single action in the past).