"i love everything about you" is a superficial way of saying i love you. it implies you like the way they look, hanging out with them and so on. it implies the love is dependant on enjoying the aspects of this person. but that such love may not stand up to seeing something in the person that you dont like. which in any long term relationship is inevitable.
"i love you" means, as a person, above and beyond all, i love you. you, everything about who you are, flaws and all i love you. pros and cons i love you. this is a much higher level of love.
i may be splitting hairs and it may be subtle but think these are very different statements. the first emotion may come after being with a person for a few weeks. while the other emotion may not follow for quite some time. depending on the people and the relationship.
just my 2 cents.