They are similar. Both can be, often are, called Bakelite. They are not celluloid (French Ivory; have grain like ivory). Generally bakelite is dark brown; catalin comes in many colors. Look here:
http://www.ebay.com/gds/Bakelite-Catalin-All-you-need-to-know-Testing-/10000000000748322/g.html
Robt.