Republicans-Ban abortion, oppose gays, destroy the social safety net, keep ruining the environment
Democrats-Right to choose, support gays, protect and expand the social safety net, and at least they have a better track record on the environment (not happy about Keystone).
Anyone who thinks the parties are the same hasn't done much research or is focusing on their favorite party not being as bold as they want them to be.
If they were the same party they wouldn't have two different names. Plus democrats are more often the not liberals while republicans are more often then no conservatives. It would be a very grave and headache inducing mistake to go up to either one and tell them they are no different than the other.