"Real love" generally pertains to the quality of the love (as opposed to, say, fake love, like physical attraction, loving someone for their money, etc).
"True love" is half-idomatic, and used almost exclusively to indicate the measure of love between two people, in the sense of having found the right one. For instance, when you see a couple sitting on a bench, all lovey-dovey, you'd say: "It's true love!" Or, "I found my true love!"