The Collaborative International Dictionary of English v.0.48:

Petrolatum \Pet`ro*la"tum\, n. (Chem. & Pharm.)
   A semisolid unctuous substance, neutral, and without taste or
   odor, derived from petroleum by distilling off the lighter
   portions and purifying the residue. It is a yellowish,
   fatlike mass, transparent in thin layers, and somewhat
   fluorescent. It is used as a bland protective dressing, and
   as a substitute for fatty materials in ointments. --U. S.
   Pharm.
   [1913 Webster]

   Note: Petrolatum is the official name for the purified
         product. Cosmoline and vaseline are commercial
         names for substances essentially the same, but
         differing slightly in appearance and consistency or
         fusibility.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Vaseline \Vas"e*line\, n. [Said by the manufacturer to be
   derived from G. wasser water + Gr. 'e`laion olive oil.]
   A yellowish translucent substance, almost odorless and
   tasteless, obtained as a residue in the purification of crude
   petroleum, and consisting essentially of a mixture of several
   of the higher members of the paraffin series. It is used as
   an unguent, and for various purposes in the arts. See the
   Note under Petrolatum. [Written also vaselin.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

Vaseline
    n 1: a trademarked brand of petroleum jelly