The new Pixel 8a looks similar, but there are probably subtle differences to the regular Pixel 8.
Google is probably banking on differentiation again when it comes to the Tensor chipset. Again, there should be differences when you compare the Tensor G3 from the top models (Pixel 8 and 8 Pro) to the variants of the upcoming Pixel 8a. There are differences in production levels.
To make it really short: Tensor G3 in the upcoming Pixel 8a should Semiconductor materials, circuits etc. and will be manufactured separately with less modern standards. This can make the difference in how well the chipset performs in everyday life. An effect on thermal management, for example, is possible.
Even with the Pixel 7a, I noticed more of a difference in everyday life than I could have imagined. The mid-range phone didn’t perform as well as the Pixel 7, even though the devices are essentially identical. The Pixel 8a may have noticeable differences from the Pixel 8.