Vegans don't consume any animal products, whereas vegetarians typically eat no meat but may eat dairy.
Ethical vegetarians are vegetarians for primarily ethical reasons. For example, they may think meat-eating causes excessive suffering (I fall into this category). Most Western vegetarians are ethical vegetarians, but some people are vegetarian for medical or religious reasons.
People are vegan or vegetarian for various reasons, health, environmental or ethical. An ethical ovo-lacto vegetarian doesn't make much sense to me since the dairy industry is pretty cruel, egg production isn't great either.
I wouldn't call myself an "ethical ovo-lacto vegetarian" because it sounds pompous, but it's basically what I am. My position is that raising and killing animals for meat is unjustifiable by any reasonable ethical or environmental standard. However, it is possible for dairy and egg production to be ethical, even though it often isn't in practice. So, I try to source eggs and milk from producers who minimize suffering. For example, I could get eggs from a local smallholding where I can see for myself that the chickens live fairly good lives.
I had a similar mindset and was vegetarian for around 7 years. My girlfriend 3 years ago challenged me on some of my thoughts and I bit the bullet and stopped eating all animal products. The transition is a lot easier if you’re already vegetarian and the amount of options around now make it really easy.
Perhaps it's someone who doesn't think in absolutes: sees the value of the ethical argument, but allows that other factors may dominate depending on the circumstances.
