jupchurch...significant difference!
Most seal coats are made from coal tar emulsion (though some are asphalt) and are placed in such thin coatings that they are essentially "paint" on the pavement.
A slurry seal is asphalt based and actually bonds to and offers some protection for the existing asphalt as well as providing flowable crack sealing capability that the spray applied seal coats don't provide.
I do not specify seal coats. I only recommend slurry seals if the pavement needs sealing.