Nothing stays the same. Can I claim to be an Andriod developer with 20 years experience? No. Its too new; there might be a couple of individuals with two years experience. Likewise I have been a UNIX sysadmin consultant for 20 years and its amazing how varied the gigs can be even within this confine. Chip has perfectly defined the consultant in his piece; its about experience and having an open mind to learn new things. Also be prepared to throw away any theories or concepts you build up along the way; you will do a gig that completely turns around your theory on how something should be done! Expert=has alot of experience and has seen things done many different ways to be able to add value.