Hard-core and Hard-line

Hard-core adjective - Firmly established over time.

Hard-line and hard-core are semantically related in diehard topic. In some cases you can use "Hard-line" instead an adjective phrase "Hard-core".

Hard-line adjective - Not allowing for any exceptions or loosening of standards.

Hard-core and hard-line are semantically related in firm topic. Sometimes you can use "Hard-core" instead an adjective phrase "Hard-line".