I was looking at this answer and I discovered the word ぜんしゅう (last week). I am familiar with せんしゅう, and I was wondering if there is any difference in meaning between them?
「[先週]{せんしゅう}」 can only mean one thing -- "last week", the week before this week. Your stand point is right this moment -- the present.
「[前週]{ぜんしゅう}」 has two meanings:
1) same as 先週.
2) the preceding week of a particular week in the past that one is talking about. Your stand point is in the past, not the present moment. It can be a few weeks ago, many months or even years ago.
You will always be able to tell from the context which meaning 前週 is being used for.