Treatments
They are generally longer than synopsis and are also more dramatic its purpose is to create curiosity and enthusiasm for your script.
synopsis
This is generally shorter than a treatment it basically sums up the whole plot and are generally a page.
loglines
loglines as the shortest and is solely for selling purposes.
for more in formation go to http://docs.google.com/View?docid=dcmjszph_298xgcxd73v