What’s the difference between registrar and DNS host?

Two separate functions that can be at different providers:

Domain registrar:

Where you purchased/registered the domain

Manages domain ownership and renewal

Controls nameserver delegation

ICANN-accredited entity

DNS host:

Where your actual DNS records live

Where you add MX, TXT, CNAME records

Runs nameservers that answer DNS queries

Relationship: You tell your registrar which nameservers to use. Those nameservers (DNS host) serve your records.

Many people use their registrar for DNS hosting. But you can use any DNS host by updating nameservers at your registrar.

The government office where you registered your ship versus the harbor authority where you file your manifests.