Are there any differences between them? Do they both mean "I think that..." in English? Thanks in advance.
2
Yes, they're not interchangeable.
"je trouve ça" is followed by an adjective, and can be translated by "I find it ..." rather than by "I think that ...".
Je trouve ça beau = I think it's beautiful
Je trouve ça bizarre qu'il soit parti aussi vite = I find it weird that he left so quickly
"je trouve que" is followed by a clause. that is often omitted in English.
Je trouve que tu devrais faire plus d'efforts = I think you should make more efforts
Je trouve que ça te va bien = I think it looks good on you
Note that you can "transform" sentences with je trouve ça to use je trouve que by adding c'est before the adjective, making it a clause.
Je trouve ça bizarre
Je trouve que c'est bizarre
