My Mom says that the Three Musketeers bars used to come in three different sections that you ate together, or something like that…I will have to ask her again next time I am on the phone, she said something about it years ago.
In the US:
The Old Mars Bar (pre 1963) was a flat slab of nougat topped with two to three whole almonds, the whole thing enrobed in chocolate. The New Mars Bar is smaller than a Milky Way, but still squarish, the nougat filled with chopped almonds (whole almonds now being too expensive) and then enrobed in chocolate.
The original 3 Musketeers (pre 1954) was indeed a three part bar: one part strawberry, one part vanilla, one part chocolate. Kind of a Whitmans’ Sampler in a wrapper. The first three flavors were not as popular, so now it’s all chocolate.
These are all made by the Mars/M&M corp, not Hersheys.
Bah. Everyone knows that Skor and Eatmore’s rule! 
Fry’s “Five Boys” chocolate, anyone?
the milky way is the candy bar that helps you work, rest, and play.
the 3 musketeers is the one that is fluffy not stuffy.
It appears as if the question has been answered, but I would like to point out that it was asked and answered in May http://boards.straightdope.com/sdmb/showthread.php?threadid=23610 We also learned that the Snickers bar was named after a horse.
Zenman said
They continued to have a three part bar with uniform flavor, until, my guess is 1960 or so I used to eat them. Today, I would have to hurl if I encountered one today. The only saving grace about the old days is, a nickel in the machine gave you a candy bar.
The milky way has fluffy whipped choclate stuff in it not nugart or gooey homogenous stuff. theres no caramel in the Aust one.
The Brit/Aust Mars Bar has fluffy whipped choclate stuff, caramel and peanuts. The fluffy whipped choclate is at the bottom and the caramel and Pnuts R mixed on top of it and then its covered in chocolate
The US Mars Bar seems to have hard Nugart and some kind of nut mixed in it and its covered in chocolate.
SKYBARS! I still see them occasionally. They
have four sections–vanilla, carmel, chocolate,
and peanut–covered with milk chocolate.
As a follow on question, and one that I think really needs an answer to: Exactly what is nougat? What is it made of? and why do we eat this stuff?
I thought nougart was hard white stuff thats in the yellow and black tolberones .oO(mmmmmm…yellow tolberones) we eat itcos it taste deliciously nice and its made of sugar so I need to fill my addiction. 
and if U dare want to know what its made of go to http://www.inil.com/users/claridge/veg/moreinfo.htm#surprise and go down to gelatin…
Anyone ever try a Big Turk? I mean, what the hell are htinking with this one? It’s like… a giant gooey pseudo-jujube. I couldn’t even eat the whole thing.
What did I expect… With a name like Big turk…
Ooh, baby, whenever I’m overseas I always snarf up the LION bars. I think Cadbury makes them. The American equivalent would be a Kit Kat bar enveloped by a $100,000 Bar. Heaven!
Those Brits have got the chocolate thing down baby. Say what you will about the rest of their cuisine, but can’t no one touch 'em when it comes to sweets. IMHO.
There are no peanuts in a British Mars Bar. Are you thinking of a Snickers Bar? (formerly known here as a Marathon)
whoops! yes I was thinking about snickers…Mars bars have no peanuts it just has fluffy choc stuff and caramel. right?
Yes, a frozen UNO bar.
http://www.britannica.com/bcom/eb/article/2/0,5716,120862+6+111134,00.html?query=nougat
The description takes a bit of the yumminess out of it, though.
P.S.: Up here, in Canada, we have dark chocolate Mars bars.
PP.S.: No true chocolate lover would dare come close to milk chocolate. A genuine sacrilege!
Well, that URL didn’t works that well, did it? One more try…
http://www.britannica.com/bcom/eb/article/2/0,5716,120862+6+111134,00.html?query=nougat