Why Does the EWS Reservation Make My Brain Hurt?

Aaj mein hoon chaar din se confused. Kuch log kehte hain ki EWS (Economically Weaker Section) reservation hai, phir kuch log kehte hain ki yeh sabhi non-Scheduled Castes aur non-Scheduled Tribes ke liye nahin hai. Bas, EWS ke people jo poor hai, unhe reservation mil sakta hai. Lekin yeh kaise hoga? Abhi tak nahi samajh paa raha hoon ki why kya reservation ke liye poor se bhi differentiate kiya ja raha hai. Kya sabhi poor nahin hain, ya kuch log poor nahin hain? EWS ki definition kya hai?