Appanently it needs to be said again

Counterpicking is picking a champion to counter another champion.

Counterplay is a way of playing that specifically counters a champion.

Counterpicking is a part of Counterplay, but it isn't a simple term. You have to walk the walk. I say Akali has no counterplay but in reality, big AoE champs or well placed skillshots make her feel like garbage. If you don't have AoE and can't hit her, well... It falls on your shoulders.

well what is counter play?

having an ability or a kit that allows you to counter what you are facing?

therefore picking a champ that has this vs a certain match up is counter play via counter picking