Same search, two different maps
Search “plumber Cologne” from a desk and from a phone standing on a street corner, and the three businesses Google shows in the local pack can be genuinely different — not because the ranking changed, but because the search itself carried different location data. Both results are accurate. They’re just accurate for different starting points, and a business that only ever checks one device type only ever sees one of the two versions.
What actually changes between the two
The local pack ranks businesses partly on proximity: how close the person searching is to each candidate. A mobile device typically supplies a precise GPS coordinate as that location input. A desktop browser generally can’t do that — it falls back to a coarser signal, commonly IP-based geolocation or whatever location a person has manually set — which can land meaningfully farther from their actual position than a phone’s GPS would. Feed a different location into a proximity-weighted ranking and the ranking itself can shift, even though the keyword and the business’s own signals never changed.
Why this isn’t just a UI quirk
This isn’t a formatting difference between two screen sizes — it’s a real difference in which businesses get shown. A business that only ever pulls its ranking from a desktop check can be looking at a rosier picture than the one most of its actual customers see if they’re searching from their phones on the move, which describes a large share of local, “near me”-style intent by nature. The reverse is just as real: a business whose customers research carefully at a desk before calling can be over-indexing on a mobile number that isn’t where the buying decision happens.
Tracking both instead of guessing
A geo-grid scan makes this checkable instead of assumed: every point on the grid can run as a desktop or a mobile query, so the same coordinate can be scanned both ways and compared directly. If the two line up closely, one device is enough for routine tracking. If they diverge — a business that looks strong on desktop but fades on mobile a few streets out, for instance — that gap is worth knowing before it shows up as an unexplained drop in calls. It’s the same principle behind why a Google Maps ranking depends on where the search happens: a ranking is only ever a description of the exact conditions it was measured under, and device is one of those conditions.