Hello,
Normally when some I hear people talk about field lacrosse it is to describe the game played on an outdoor field. The other type is called indoor or sometime box which is played on a field the size of an ice rink covered in Astor tuff.
Field lacrosse played at NFHS, NCAA , and pro levels (so yes there is still organized field lacrosse). The NCAA rules are at
http://www.ncaa.org/library/rules/20...osse_rules.pdf
Hope this helps. If you have any other questions just ask.