pulley block vs bollock

pulley block and bollock both are nouns.

Word	Noun	Adjective	Verb	Adverb
pulley block	Yes	No	No	No
bollock	Yes	No	No	No

As nouns, bollock is a hyponym of pulley block; that is, bollock is a word with a more specific, narrower meaning than pulley block:

pulley block: a simple machine consisting of a wheel with a groove in which a rope can run to change the direction or point of application of a force applied to the rope
bollock: a pulley-block at the head of a topmast

Other hyponyms of pulley block include bullock block, fairlead, idle pulley, idle wheel, idler pulley.

pulley block (noun)	bollock (noun)
a simple machine consisting of a wheel with a groove in which a rope can run to change the direction or point of application of a force applied to the rope	a pulley-block at the head of a topmast
	one of the two male reproductive glands that produce spermatozoa and secrete androgens