Full Answer

The two engines take opposite approaches to citation. Perplexity numbers every source inline, displays clickable links beneath each answer, and sends a clean referrer header when a user clicks through. That header lands in GA4 as identifiable traffic with no extra configuration. ChatGPT, by contrast, paraphrases heavily and cites only when the answer relies on a specific claim — and even then, its mobile app often drops the referrer entirely, so the visit shows up as direct traffic instead.

The data bears this out. Across 73 WooCommerce stores, ChatGPT accounts for 88.1% of AI referral volume, yet a significant share of those visits arrive without attribution because of inconsistent referrer behaviour (Shero, 2026). Perplexity sends far fewer visits in absolute terms, but nearly all of them are correctly attributed — making it the easiest AI source to track in GA4.

For content strategy, the difference matters. Perplexity rewards well-sourced, clearly structured pages — if your page carries the best answer with a cited statistic, Perplexity will number-link it. ChatGPT rewards self-contained, quotable facts it can paraphrase into a conversational answer, especially product schema and FAQ blocks. Tracking both engines accurately requires separate measurement approaches because their referrer patterns are fundamentally incompatible with a single attribution model.