SPL & Design Proposals

What is the difference between SPL Token, on-chain Feature Proposal Program and Solana’s Design Proposal mechanism?

It seems validators have votes based on how much SPL (Feature Proposal Program | Solana Program Library Docs) they have. Once the required number of votes are tallied, the feature will be automatically activated at the start of the next epoch.

But the Design Proposals (Implemented Design Proposals | Solana Docs) says that proposals may be implemented as described, implemented differently as issues in the designs become evident, or not implemented at all - all subject to the Solana Foundation.

Could anyone please clarify for the community. Thank you