Yamaha FG820 vs Yamaha FG830

The difference between them is that the 830 has rosewood back and sides vs mahogany for the 820. The 830 costs about $50 more, probably because rosewood is a bit more rare than mahogany, these days. I'm not sure there would be any noticeable difference in playability between them.

In a nutshell, the FG820 has a slightly more mellow tone, with somewhat subdued highs, compared to the FG830. The FG830 projects a little better, and sounds more balanced (to me). The treble ranges are more prominent.