O-ring and gaskets both achieve the same goal but o-rings are always rings with differing sizes where a gasket can be any shape or size.
Mastering O-Ring Durometer Scales
7 Common Causes of O-Ring Failure
8 Types of O-Ring + Applications (Clear Guide)
New composite head gasket. Anyone using it? - NASIOC
Rubber O Rings: Types, Rubbers, Benefits, and Design
What is the difference between O-ring and gasket?
Large O-Rings: Types, Advantages & Disadvantages
O-ring VS Gasket: Which One Should You Use? - Hongju
Quad Seals Compared to O-Ring Seals, Coating Systems
Nitrile vs. Neoprene - What's the Difference?
All About Gaskets: A Comprehensive Guide