Differences in chem test results

I just got a new inground pool and have a question about testing.

I have 2 liquid drop test kits, the "instant" test strips, and took a water sample into a pool store. I'm getting very different numbers from each test and I don't know what to trust.

For Alkalinity the pool store says my sample was 100ppm. The test strips show a similar range, but my drop test kits show me 160/180ppm.

For Calcium hardness, the pool store/test strips say 110, but the drop tests show closer to 200.

For PH, pool store says 7.8 but the all my home tests say 8.5-9.5.

What tests should I trust?