Cars are an okay analogy, but I think smartphones work better.
Google designed the Android phone, they figured out how to make all the software work and what buttons you should have and what they think is the best way to build the phone. They did all the really hard work in designing a smartphone but don't really want to make their own phones because designing things takes so much effort already and the market is really competitive, so instead they license their design to other companies and let them battle out why collecting money for their design.
Samsung, HTC, LG, and Motorola want to get into the smartphone business, but designing a smartphone from scratch is expensive and difficult and costs a lot of money, so instead they use Google's Android design for their phones. Google says okay, you can use our design if your phones have at least these specific features and use our software, but you can decide how fast it is and how big the screen is and can even customize how it looks a bit and so on.
Everyone starts selling Android phones, some of them are really fast and have really big screens, those cost a lot of money, others are small and cheap but are kind of slow. They are all basically the same phone, but the more you spend the better your phone will be, and each year the phones get a little bit better but are still pretty similar to the phones from last year.
You now have to decide who's Android phone you want to buy. Do you want Samsung's with the really nice screen? Do you want LG's with the best camera? Do you want Motorola's with the huge battery life? Each company's best phone is just about as good as any others, but there might be that one specific feature you think makes one phone better than the other by just a tiny bit so that's the one you buy.