I'd like to correct the second sentence, it's simply おいくつですか。
They mean the same, in English "how old are you?".
いくつ for question is used to ask "how many...?" and in this case, "how many years (for the age)" = "how old". So, 何歳おいくつですか is incorrect for repeating "how old".
Espero que te ayude.