The A7's are all mirrorless not Digital Single Lens Reflex (DSLR). There is a fairly big difference between the 2. Biggest advantage of the A7 series is that they are all full frame, do you need full frame. The files the A7r's produce are massive and the native lens choice for the series is not great. It's a decent camera though, especially if you are using normal to long length legacy lenses with adaptors.
The A7's are all mirrorless not Digital Single Lens Reflex (DSLR). There is a fairly big difference between the 2. Biggest advantage of the A7 series is that they are all full frame, do you need full frame. The files the A7r's produce are massive and the native lens choice for the series is not great. It's a decent camera though, especially if you are using normal to long length legacy lenses with adaptors.