Just in case someone reading would like to get a Lab and doesn't know much about them yet I'd like to point out that Labs only come in three official colours, which are black, yellow and chocolate. Silver is hugely controversial and CKC membership, for one, prohibits advertising dogs as silver, meaning a breeder who does so is very likely to be a disreputable breeder. I've never seen a real live silver but the one pictured above is much less "weim" looking than most photos I've seen.
Labs do occasionnally appear in "mismarked" colours which would include the black and tan and the tan on tan shown above. As well odd spots and brindling has occurred, also long hair. These can be purebred, registered Labs but they cannot be shown in conformation.
There's a good website on mismarks here:
http://www.woodhavenlabs.com/mismarks.html I just love the yellow puppy with the musical note on his side.
Off-topic, sorry. The terms most commonly used in Labs are
field, the lankier looking (working) one, and
bench, the ones that show in conformation. "American" and "English" are also used, respectively, but are incorrect. Both types should be able to hunt and I personnally know several of each type that are. But it's mostly the fieldy type that you see in field trials.
How about the schism between field and bench English Springer Spaniels? Sorry, I can't find photos I can post but there is this site which describes the differences.
http://www.essft.com/fieldshow.html Be aware, if you google for images of each you will find bench types listed as either. I'll try later to post some photos. Too bad I don't have a good one of our own field girl but she pre-dated digital cameras.