This article article explains it nicely https://www.lawlessfrench.com/grammar/indefinite-demonstrative-pronouns/

It is the difference between this and that. Meaning an abstract reference versus a reference to something that is right in front of you - "ostensive" . It is technically wrong to use ce about something abstract, but of course like in english people break these rules. But dont worry too much just remember if its in front of you then usually ce and if its not usually ca. And pay attention to what people actually say. One exception is that people will show you how to so something and often say comme ca.

Even though they are graphically similar their uses are very different. 1. Ce = determiner for masculine singular words beginning with a consonant. Ce matin = This morning. Je n’aime pas ce manteau = I don’t like that coat. 2. Ce = pronoun Je ne sais pas ce que tu veux dire = I don’t know what you mean. (ce = the thing which you mean) Est-ce votre nom? Is it your name? Ce = the name we are not mentioning. 3. Ca = pronoun. ("Cela" is prettier in writing) Je ne mange pas ca. = I don’t eat that. Some people put “ca” at the beginning of a sentence but shouldn’t. (Ca n’est pas bon) We say: Ce n’est pas bon.