hola catherine!!! la diferencia en español no es mucha solo depende como la utilices, las dos te pueden servir como un saludo muy informal. que hay?? es mucho más común que ¿qué pasa? en un saludo. por ejemplo: que hay catherine?? es un modismo como what´s up? en ingles como contexto de una conversación que pasa?? es como que sucede???, q ocurre??? hay viene del verbo haber como x ejemplo ¿que hay en esa caja? que pasa viene del verbo pasar=to happen: "what happen?

Also, in practical terms, "¿qué hay? is usually said when your greeting someone very informally (it would be somehow equivalent to 'how is it going?'), whereas "¿qué pasa?" is used under a situation when something is happening (usually a bad thing) and you're inquiring about it. I should mention that this distinction I make about between these two phrases' use is blurry and probably not even real, or only applicable to certain regions, specially because any of these two could be applied to these two situations without being wrong (it just sounds a little weird to greet someone with '¿qué pasa?', at least in my area).

well, in english, probably there's no much difference, both can be translated as "what's up?", but in spanish que pasa refers to the verb pasar=happen, and que hay, refers to the verb haber/to have...that is the difference, they are use in spanish to inquire for different kind of info.

Que pasa is the same " What happend ? ", and Que hay, is similar in english, to say, What about with ... ?

PUEDES UTILIZARLO SEGUN EL CONTEXTO : QUE PASA? PARA PREGUNTAR SOBRE UN HECHO. QUE PASA! ES UNA ADMIRACION...Y QUE HAY? IGUAL PARA PREGUNTAR SOBRE ALGO QUE DESEAS PEDIR, TAMBIEN QUE HAY!!!! PARA SALUDAR. QUE HAY DE NUEVO VIEJO!!!! CUALQUIER OTRA PREGUNTA ME LLAMAS A MI CELU 96594508 O CORREO [email protected] LIMA PERU.