"La Diferencia" is Los Temerarios doing what they do best: a man who loves someone who will never love him back, and who refuses to stop anyway. He knows it from the first verse. She may waste her time without him, she may never even want to say his "humilde nombre" (humble name), but "de cualquier modo, yo te seguiré queriendo" (either way, I'll keep loving you).
What makes it sweet rather than pushy is how calmly he accepts it. He asks "¿Qué daño puedo hacerte con quererte?" (What harm can I do you by loving you?) and admits "sé que no nací yo para ti" (I know I wasn't born for you). He just wants to be left dreaming: "No me despiertes tú" (Don't you wake me up). There's even a spoken aside, "¡Cómo sufres Gustavito!" (How you suffer, little Gustavo!), a teasing nod to the band's singer Gustavo Ángel, with -ito being the Spanish diminutive that turns a name affectionate.
The title pays off in the last lines. The difference between them, he says, is simple: "que yo en tu lugar sí te amaría" (that in your place, I really would love you). That little sí before the verb is worth learning: it adds emphasis, like saying "I would love you".