Is this the same as the HP 10A laser cartridge?

I don't think so. You would have to contact HP support to be positive, but the 10a is for these HP printers: 2300, 2300d, 2300dn, 2300dtn, 2300L, 2300n the 305a is for these HP printers: M351, M351a, M375, M375nw, M451, M451dn, M451dw, M451nw, M475, M475dn, M475dw