Is there any difference between K-Pop and K-Rock?

Traditionally the distinction lies largely in the foundation of the Idol System.

Modern Kpop as traditionally recognized owes origins to the popularization by SM Entertainment of the application of a Japanese like idol system to the wave of new Western influenced pop that had its origins in Seo Taiji and Boys.

The idol system came to be the dominant marker of "kpop" style music. In that it was not solely focused on music per se but an all encompassing focus on groups composed of trained "idols" who were multi discipline entertainment figures serving role models, singers, dancers, hosts, personalities, and often as actors. There is a designed "aspirational role model" and "romantic appeal" element to the idol as entertainment figure that is part and parcel with being an idol that is not strictly there perhaps as sole musician or otherwise performer.

K-rock and k-rap and other facets do not strictly have kpop's idol system as their foundation, though there can sometimes be a blending element, as is the case with DAY 6 perhaps. I believe they take in many idol like characteristics due to their JYP origin.