1. There are same but link ads hard to earn because the visitor need to click on the link text AND again click on the google ads then only you will get paid 2. There are no such thing call "average CTR", it depends on many factor
Great reply as usual I would like to add a little more. 1. Your earning per click does not depends on the type of ads but it is about the advertisers side. You should better focus on keyword research before doing more further 2. You cannot rely on CTR to be a measurement on penalization or banning. Your account would be safe even if it has 100% CTR if your traffics were legit enough.