Ritek G04 is 4x DVD-R, while Ritek G05 is 8x DVD-R.
As said before, Ritek G05 has been famous for lots of defective batches degrading at a fast pace. Early G04s with a very dark-purple dye were good, but later G04s with a G05-like purple dye suffered those degradation issue too.
Anyway, 4x media is very rare now, and you should use other stuff like Verbatim or Taiyo Yuden instead. I think those should work well for backups. If you want to find some TY media in B&M store check the Taiyo Yuden FAQ.