lionxheartxsd,
Perhaps these images will clarify exactly what the differences are between buckshot and slugs:
Buckshot:
http://images.outdoorinteractive.net/mgen/284793_d.jpg
Shotgun slugs:
http://www.nrapublications.org/tah/images/slugs8.jpg
Top: rifled slug, aka: Foster-style slug; bottom: sabot slug (pronounced: say'-boh)
Foster-style slugs are designed for smooth-bored tubes (barrels), and sabot slugs are designed for rifled tubes; for further research (or "ha-ha's"), Google: "brenneke slugs". :-D