What's the difference in the usage between 懒惰 and 懒? Both can be translated as "lazy".
懒 (lazy) is mainly an adjective (less often as a noun)
懒人 (lazy person)
人懒 (the person is lazy)
懒惰 (lazy/ laziness) can be an adjective or a noun.
由于他懒惰，他的花园里充满了杂草 (Due to he being lazy, his garden is full of weeds )
由于他的懒惰，他的花园里充满了杂草 (Due to his laziness, his garden is full of weeds )
The adjective 懒惰 preceding a noun usually requires the adjectival prefix '的'
Example: 懒惰的人 (lazy person)
The adjective 懒惰 after a noun doesn't require adjectival prefix '的'
Example:人懒惰 (the person being lazy)
懒 (lazy) can also be a noun. It is used more often in spoken language compared with 懒惰(lazy). (Adding to @Tang Ho's answer)