The main difference was Matchbox was more realistic and Hot Wheels was more hot rods, fantasy cars, etc. Which meant I spent more time playing with a '73 Citroen than a metallic purple car with oversized wheels and an engine the size of my head.
Of course, when it came to accessories Hot Wheels won hands down with one of the greatest inventions ever - the plastic orange tracks (with purple connectors).
These days, the distinction between Matchbox and Hot Wheels is less significant because both brands are now owned by the same company, Mattel.
But enough of the back story, whether you choose Matchbox, Hot Wheels or both, they remain great toys. And unless you go for something fancy, they're one of the most economical toy purchases around - usually about a buck. And anyone who has ever stepped on one while barefoot can tell you how durable they are.
Presently, our house has about 6000 of these things lying around - the living room looks like the LIE on a summer Friday at 5 o'clock. So perhaps we've created a monster, but it's still worth it because I get to play with them under the guise of father-son bonding time.
Oh, and a word to the wise - stay away from the Matchbox or Hot Wheels playsets. They're really cool for the first half hour after they're assembled but once they start to fall apart or you lose pieces, your playroom will look like Fred Sanford's front yard.