There are two parts to a URL your view needs to care about: the URL path, and the query string. Both your examples are just path elements, really, the query string is everything after the ?.
It really depends on how your web application is supposed to be interacted with; a URL usually represents one resource, with the query string representing, well, a query on that resource.
Compare /users/102324 with /users?name=Joe+Soap; the former represents one user (with the id 102323, the latter URL is for all users, but includes a search for users matching a given name.
The path is the part you match with the route config; it matches your pattern exactly; for your two examples, the foo and bar placeholders capture everything (except for the / character); so both your URLs would work, and simply result in different values for foo and bar:
http://url/end_point/foo&bar -> {'foo': 'foo', 'bar': 'bar'}
http://url/end_point/var=foo&var2=bar -> {'foo': 'var=foo', 'bar': 'var2=bar'}
But you'd normally not use & in a URL path.
The query string, on the other hand is parsed for key-value pairs and can be accessed with the request.query object:
@route('/end_point')
def like_provider(self):
foo = request.args.get('foo')
bar = request.args.get('bar')