New and all improved? The UV-B5 features a channel selector (nice) and an alarm button (who cares) on top, but lacks a flashlight. The UV-B6 features a flashlight but lacks the channel selector and alarm button on top. All other specs are identical.
The batteries look very similar to the ones we know from the Baofeng BF-666/777/888 series, but the shape of the contacts is different. I’m pretty sure they’re not interchangeable.
Prices vary from $53 for the UV-B5 version to $58 for the UV-B6 version (409shop, shipping included).
| Place of Origin | China (Mainland) |
|---|---|
| Brand Name | BAOFENG |
| Model Number | UV-B5 |
| Type | Handheld |
| Dimensions | 116.2mm * 57.9mm * 35.7mm |
| Frequency Range | 136-174 & 400-480mhz |
| Memories | 99 |
| Talk Range | 5-10km |
| Product Name | radio transmitter |
| Model NO. | BF UV-B5 |
| Color | Black |
| R.F. Power Rating | 5W |
| Operating Voltage | 7.4V |
| Standard Battery | 1800MAh Li-ion |
| Standard Accessory | Radio, charger, battery, dual band antenna, strap, belt clip |
| Weight | 0.8kg |
| Place of Origin | China (Mainland) |
|---|---|
| Brand Name | BAOFENG |
| Model Number | UV-B6 |
| Type | Handheld |
| Dimensions | 116.2mm * 57.9mm * 35.7mm |
| Frequency Range | 136-174 & 400-480mhz |
| Memories | 99 |
| Talk Range | 5-10km |
| Product Name | 2 way radio |
| Model NO. | BF-UV-B6 |
| Color | Black |
| R.F. Power Rating | 5W |
| Operating Voltage | 7.4V |
| Battery Capacity | 1800MAh Li-ion |
| Standard Accessories | Radio, charger, battery, dual band antenna, strap, belt clip |
| Weight | 0.8kg |
Ham Radio Blog PD0AC 
My guess is that the UV-B6 version, is the safest bet, because it has no rotary for the channel/frequency tuning, sometimes one which does, fails easily, due to hf.
Mine is getting plenty use, and no problems.
How should RF get in the encoder ? I don’t QSY when key’d. 😉