Traditionally, a "liberal" -- in Europe especially -- has been someone who values individual freedom and who wants government to back off and not oppress people. You can see that a liberal would oppose slavery -- and also oppose welfare, social security, progressive taxes, and obamacare.
On the other hand, a "Liberal" is someone who values groups and the common good and takes a very "open" or "Liberal" view of the power of government for good. Government should take an activist role and do its best to build a utopia where bad things never happen.
“on the other hand” should read “But, in today’s accepted revised usage as defined by the progressive movement”