and the Wyeast 'propagator' packs are specifically designed to be used in a starter. the 'activator' packs claim to be pitchable, however they are below optimal pitching rates.
the vials from White Labs have about as much yeast in them as an 'activator'. you can direct pitch either, but a starter is a better route to take. and if its a higher gravity beer (over 1.060 OG) then you really need to make a starter.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10