What overlaps
Everything technical. If a model cannot crawl or render your page, it cannot cite you. Site speed, clean HTML, internal linking, sensible information architecture and a robots file that does not block AI crawlers are shared prerequisites.
Authority overlaps too. The sources models trust are broadly the sources Google trusts, because both are trying to answer the same question about who is reliable.
What differs
Format. SEO rewards depth and comprehensiveness on a page. GEO rewards extractable, self-contained passages that make sense when lifted out. A 3,000 word guide can rank while contributing nothing quotable.
Measurement. There is no rank tracker for being mentioned. You measure GEO by running your buyer questions through the assistants regularly and logging whether you appear, in what context, and against which competitors.
How to run them together
Do not build a separate GEO team or a separate content stream. Add the answer-first structure to how you already write, get the entity and schema work done once, and put citation-earning coverage into your PR brief. It is one programme with two scoreboards.