Difference between site and block plan?

The scale foremost. While site plans are normally 1:100 (or at the same size as the building plans), block plans are usually at 1:500 or larger.

A site plan "usually shows a building footprint, travelways, parking, drainage facilities, sanitary sewer lines, water lines, trails, lighting, and landscaping." While the block plan puts more emphasis on the position of the site.