のに: although, even though

のに marks a contrast that surprises or disappoints the speaker — a nuance the plain “but” が does not carry. Both are here, so the difference is easy to see.

Also known asnoniのにalthough japaneseeven though

～が、～が — but (joining two sentences)

But / although

が after a full sentence means “but”: 〜ですが、〜です.

日本の　食べ物は　おいしいですが、高いです。

にほんの　たべものは　おいしいですが、たかいです。

Japanese food is tasty, but expensive.

This が joins two sentences that contrast. It is not the subject particle: it comes after です or ます and is followed by a comma, and the first sentence keeps its polite ending.

In the textbooksMinna I, lesson 8

～のに、…のに — although / even though

But / although

Contrary to expectation: “although A, (unexpectedly) B”.

約束したのに、彼は　来ませんでした。

やくそくしたのに、かれは　きませんでした。

Even though he promised, he didn't come.

のに joins two clauses where the second is contrary to what the first leads you to expect, often with a nuance of surprise, dissatisfaction or regret. Na-adj/noun add な: 元気なのに.

In the textbooksMinna II, lesson 45