What is the difference between within and inside?
I've read a lot of letters with these words and people say that they mean the same.
Dictionaries often use the word inside in their definitions of within. Here's an entry from Oxford Dictionaries Online:
‘the spread of fire within the building’
1.1 Inside the range of (an area or boundary):
‘property located within the green belt’
1.2 Inside the range of (a specified action or perception):
‘we were within sight of the finish’
1.3 Inside the bounds set by (a concept, argument, etc.):
‘full cooperation within the terms of the treaty’
Are there any semantic or grammatical differences between these two words?