Let $X$ be a topological space.
Halmos calls "reduced Borel algebra" the quotient $B(X)/M(X)$ where $B(X)$ is the Borel field of $X$ and $M(X)$ is the $\sigma$-ideal of meagre subsets of $X$.
Fremlin calls "category algebra" the quotient $BP(X)/M(X)$ where $BP(X)$ is the Baire property algebra, i.e. the $\sigma$-field of subsets of $X$ having the Baire property (BP), and $M(X)$ is the sigma-ideal of meagre subsets of $X$.
I know that every Borel set has the BP (besides, it is an argument that Halmos uses to prove that $RO(X)$ (i.e. the regular open algebra of $X$) is isomorphic to $B(X)/M(X)$).
However, I wonder:
(1) What are the difference (if any) between $B(X)/M(X)$ and $BP(X)/M(X)$?
(2) If there are differences, how much does it depend on the topology of $X$ itself?
(3) Is it possible to prove that $RO(X)$ is isomorphic to $B(X)/M(X)$ without using the BP?
Many thanks in advance for any input and/or reference.