i cant speak to GA but just dropping by to point to the docs
https://www.netlify.com/docs/analytics/ for details on the numbers. it’s IP based, and some filtering is done as described
“The Pageviews and Top pages charts include only responses with Content-Type: text/html and a status code of 200, 201, or 304. We filter the data by status code this way so that we don’t count errors or double count redirects. This also applies to the Pageviews total for your site.
Unique visitors counts different IP addresses engaging with your site within a single day. If someone loads pages of your site on multiple different days, they will be counted as a unique visitor for each day. The Unique visitors total for your site is a sum of the daily numbers.”