What's the difference between a Hermès Birkin and a Hermès Kelly Bag?

Can you tell the difference between Hermès Birkin and Kelly bags?
I thought about this a few years ago one night while I was watching a repeat episode of "Sex And the City"  seeing Samatha’s bag, and then realizing that I wasn’t sure which one it was.

Yeah I know in that episode they keep saying Birkin, Birkin , Birkin!!! So it was kind of obvious which one she was referring to, a few days later I made my way to the Hermès store, I was looking and admiring the bag they had in the window display and made my way inside the store and asked the sales associate if it was possible for me to check out the beautiful black Birkin they had in the window display, she looked at me like if I was an idiot and she said "that's  not a Birkin , that is a Kelly", (OMG, OMG , OMG!!, what have I done? thats's what I thought, so embarrasing confusing such iconic bags, and there is when I get my first proper Hermès lesson.
So this is a little bit of what I learned.

About both bags.
Prices for both begin around $10,000 and can go well beyond $50,000
Part of the price of all Hermès bags is the privilege to bring it into any boutique to be sent to Paris for a “spa treatment” where the bag, no matter how old or abused, will be bought back to the best possible condition…for an additional cost of several hundred dollars
Both bags can be customized to the buyers specifications
Locks and keys are number-coded
Lining is usually made of goat skin that matches the color of the exterior skin
Identifiable by their metal-tipped clasp, which can be closed with a tiny padlock (and the clasp’s hidden key often dangles from the handle in a leather sheath of its own)
Not sold online and never ever will be
Famous for their waiting lists (Like on Sex and the City when Samantha used Lucy Liu’s name to score the red one faster?)

The Hermès Kelly Bag:

• It has only one handle (the most noticeable difference)
• Named after Grace Kelly
• Became famous in 1956 when Grace Kelly (then Princess of Monaco) used one to shield her pregnant stomach from the prying eyes of the paparazzi
• More formal than the Birkin
• Comes in different sizes.
• It takes a single craftsman about 18 hours to make one.

The Hermès Birkin Bag:

• It has 2 handles (the most noticeable difference)
• Named after Jane Birkin (who has an interesting history with the company)
• 5 Birkins are produced a week at the Hermès Atelier in Paris
• More casual than the Kelly & has a slightly younger more bohemian appeal
• With an open top, it is easier to open than the Kelly

Nowadays I am obsessed with either bag, but I think I preferred the Birkin, it is really dreamy.
Do you think they are worth the price? I do.