I've seen that these two smart contracts are often used, and the ETH is widely used more often than WAVES. What is the difference between the two platforms?
Waves is not a smart contract plattform - it is a plattform to issue tokens on a very, very simple way (tokens dont have any functionality).
Waves also has a so called DEX (decentralised exchange), where you can trade the tokens of the waves plattform.
This one is true, however in my own opinion waves interface is more user friendly compared to ethereum platform. But, both of them are good, each has different characteristics. Some coins are not registered in waves, and some are not open in eth, vice versa. So, just choose which is more convenient for your coins and tokens.
yes right they are both good but different characteristic that both usable just what you have told that some coins can access or registered in waves and some are in eth so both are can use in a way where we can use on the other hand on how does waves and eth are moving this is why they can compared interms on their platform.