Birch Bay are made by Clearwater. They still use balboa controls and aqua-flo pumps. Some of the differences are:
- The synthetic cabinet is stronger in the Clearwater line
- Things that are standard on most Clearwaters are options on Birch Bay, like ozone, circ pump, LED, waterfalls, etc.
- Birch Bay uses a wood frame, though it is not structural
- The warranty is a little shorter in Birch Bay
The reason for the confusion is because up until recently, the XS series was clearwater's lower end line. There are some Birch Bays that are more expensive than the XS series because the Birch Bay would be larger and have more jets. The differences that I listed above still mostly apply though.
All of this said, the Birch Bays are great tubs when it comes to bang for buck. Imo, they have the strongest shell in the industry. This is backed up by the best shell warranty in the industry, 20 years on structure and surface. I think the next closest surface warranty is 7 years. That's a big difference. Keep in mind, Birch Bay only has 10 year structure and surface, but it is made the exact same way as the full Clearwater line. The 2 lines are actually very similar. They use some old molds for the Birch Bay, which is another way they are able to lower the cost.
They are not one of the big 5 mentioned here all of the time, but I think they are excellent tubs.