Every $S_1(B_\Gamma,B_\Gamma)$ space is a $\sigma$-space, and the property $S_1(B_\Gamma,B_\Gamma)$ is hereditary for subsets (B. Tsaban and M. Scheepers, The combinatorics of Borel covers, Topology and its Applications 121 (2002), 357-382.)

For example, a Sierpi'nski set satisfies $S_1(B_\Gamma,B_\Gamma)$.

On the other hand, it is very difficult to be a Q-set. For example, Q-sets have Lebesgue measure zero. In particular, they cannot be Sierpi'nski.

Every $S_1(B_\Gamma,B_\Gamma)$ space is a $\sigma$-space, and the property $S_1(B_\Gamma,B_\Gamma)$ is hereditary for subsets (B. Tsaban and M. Scheepers, The combinatorics of Borel covers, Topology and its Applications 121 (2002), 357-382.)

For example, a Sierpiński set satisfies $S_1(B_\Gamma,B_\Gamma)$.

On the other hand, it is very difficult to be a Q-set. For example, Q-sets have Lebesgue measure zero. In particular, they cannot be Sierpiński.