DNSSEC strengthens authentication in DNS using digital signatures based on public key cryptography. With DNSSEC, it's not DNS queries and responses themselves that are cryptographically signed, but rather DNSdata itself is signed by the owner of the data.
DNSSEC explanation provided by ICANN.org
DNS over TLS
DNS over TLS (DoT) is a security protocol for encrypting and wrapping Domain Name System (DNS) queries and answers via the Transport Layer Security (TLS) protocol. The goal of the method is to increase user privacy and security by preventing eavesdropping and manipulation of DNS data via man-in-the-middle attacks.
DNS over TLS explanation provided by Wikipedia.org