What distinguishes a qualified certificate, a regulated certificate, a qualified electronic signature and an electronic seal in Swiss law?

A qualified certificate is issued to a natural person and meets ZertES; a qualified electronic signature (QES) must rest on one and is legally equivalent to a handwritten signature (OR Art. 14 para. 2bis); a regulated certificate is issued to a natural person or a UID entity under ZertES and can be used for electronic seals or website authentication; an electronic seal is an electronic signature for organisations, in Switzerland bound to a regulated certificate.

Note the difference to the EU: under eIDAS 2024/1183 "qualified certificate" is broader and also covers seals and website authentication.

Go deeper:

• eIDAS (Wikipedia) — the EU counterpart: qualified certificates, qualified signatures and seals.