safe sex vs sexual practice

safe sex and sexual practice both are nouns.

Word	Noun	Adjective	Verb	Adverb
safe sex	Yes	No	No	No
sexual practice	Yes	No	No	No

As nouns, sexual practice is a hypernym of safe sex; that is, sexual practice is a word with a broader meaning than safe sex:

safe sex: sexual activity (especially sexual intercourse) with the use of measures (such as latex condoms) to avoid the transmission of disease (especially AIDS)
sexual practice: activities associated with sexual intercourse

Other hypernyms of safe sex include sex, sex activity, sexual activity.

safe sex (noun)	sexual practice (noun)
sexual activity (especially sexual intercourse) with the use of measures (such as latex condoms) to avoid the transmission of disease (especially AIDS)	activities associated with sexual intercourse