The Difference Between Envy And Jealousy

Midoriya Izuku wasn't a jealous man. He was content with his life. He was married to Ground Zero, the third ranking pro hero and steadily climbing, he was the new Symbol of Peace and, Omega advocate.
Yet why does he feel his stomach twist when he sees Shouto pressing his hand against Eijirou's stomach, heating to show he was there for his pups while Eijirou smiles- like he wished that Shouto did that for him against his stomach for pups he wished he had?
Bakugou Katsuki wasnt a jealous man. He was content with what he had. He was THE Ground Zero that put other alphas to shame, 3rd ranked hero and married to THE Deku, Symbol of Peace.
Yet, why does he feel his chest hurt when he sees Eijirou, carrying Shouto's pups, holding onto him during the gender reveal, happy before they kiss, like he wished he was the one to get kissed and loved like that by Eijirou?
They weren't jealous, they realized.They were very much envious.
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After learning his husband was having an affair with his own rival, a pregnant Kirishima Eijirou finds solace in Todoroki Shouto in the middle of it all. Neither Bakugou or Midoriya approve of this new found solace in the slightest.
But neither could stop it.