Ce, cette, cet, and ces are demonstrative adjectives, which are used to indicate a specific noun or nouns. In French, they must agree with the noun(s) in number and sometimes gender.
Demonstrative pronouns (celui, celle, ceux, celles) replace a specific noun that was mentioned previously. In French, they must agree with the noun(s) in number and gender.
Indefinite demonstrative pronouns (ce, ceci, cela, ça) do not agree with the nouns they replace in gender or number.