Heimdal vs Heimdallr

Heimdal and Heimdallr both are nouns.

Word	Noun	Adjective	Verb	Adverb
Heimdal	Yes	No	No	No
Heimdallr	Yes	No	No	No

As nouns, Heimdal and Heimdallr are synonyms defined as:

Heimdal and Heimdallr: (Norse mythology) god of dawn and light; guardian of Asgard

Other synonyms of Heimdal include Heimdall.

Heimdal (noun)	Heimdallr (noun)
(Norse mythology) god of dawn and light; guardian of Asgard	(Norse mythology) god of dawn and light; guardian of Asgard