We sometimes use real and really interchangeably, but there is a definite distinction between these two words.
Real is an adjective. Use real to describe a noun when you want to say that the object is genuine or true.
My ring has a real diamond.
I saw a real elephant at the zoo.
If this is real love, it will last.
Really is an adverb. Use the adverb really to modify the action of a verb.
I really hope the weather is nice tomorrow.
I’m surprised that she’s really crying rather than faking it.
As an adverb, really can also modify and intensify an adjective (describing word).
Bob is tired. (tired describes Bob)
Bob is really tired. (really intensifies the adjective tired)
Sara was helpful yesterday. (helpful describes Sara)
Sara was really helpful yesterday. (really intensifies the adjective helpful)
Officially, you should use real to modify a noun and really to modify a verb or an adjective. However, our language use is getting more relaxed, so don’t be too hard on yourself if you choose to use real where really really needs to go.