vs
QUICK ANSWER
"¡Ja!" is an interjection which is often translated as "Ha!", and "no te creo" is a phrase which is often translated as "I don't believe you". Learn more about the difference between "¡Ja!" and "no te creo" below.
¡Ja!(
hah
)An interjection is a short utterance that expresses emotion, hesitation, or protest (e.g., Wow!).
a. Ha!
Me dijo que el auto era suyo. ¡Ja!, sé de buena tinta que es de su hermano.He told me the car was his. Ha! I know very well that it's his brother's.
no te creo(
noh
teh
kreh
-
oh
)A phrase is a group of words commonly used together (e.g., once upon a time).
1. (general)
a. I don't believe you
No te creo cuando dices que me odias.I don't believe you when you say you hate me.