Base64 represents bytes as text so a text-oriented channel can carry them; anyone can decode it. URL percent-encoding protects the structure of a URL by escaping characters inside a component. Encode a query value, not an entire already-assembled URL, or separators may stop working as intended.
A hash produces a digest useful for comparing data, but a plain digest does not prove who supplied it. Use a MAC or signature when authenticity matters, and encryption when secrecy matters. Passwords need a dedicated salted password-hashing method rather than a quick general-purpose hash. The Base64 and URL encoding tools help with representation, not access control.
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