The Pixel 4a and Pixel 4a (5G) will bear an uncanny resemblance to each other, according to a leak published by @ImjustSayingJC. Citing "information provided to me", @ImjustSayingJC claims that the Pixel 4a (5G) will have a 5.81-inch display, which is the same size as the one in the Pixel 4a. If that is the case, then we would expect the Pixel 4a (5G) to share the same chassis as the Pixel 4a too.
Additionally, @ImjustSayingJC states that the Pixel 4a (5G) will also have a capacitive fingerprint scanner and a single rear-facing camera. Presumably, these will be the same components with which Google has equipped the Pixel 4a.
The main differences between the Pixel 4a and Pixel 4a (5G) will be internal. As its name suggests, the Pixel 4a (5G) will have a 5G modem. @ImjustSayingJC states that this will come courtesy of the Qualcomm Snapdragon 765G, which is the same chipset that Google will apparently use in the Pixel 5.
Google is expected to announce the Pixel 4a (5G) and Pixel 5 in October. The company has already confirmed that the former will start at US$499, which would make it US$150 more expensive than the Pixel 4a. We would not be surprised if Google equipped the Pixel 4a (5G) with a larger battery than the Pixel 4a because of its more powerful SoC and 5G modem. Even then, a 43% price increase for the Snapdragon 765G, 5G connectivity and potentially a larger battery seems rather steep to us.