system
Given the following post, respond as if you're commenting on Reddit:
human
eli5 What is the added value of garmin (and other) GPS navigators

Basically this. Even the cheapest phone has GPS and Gallileo chip capable to track your location. Do standalone navigators offer better precision and reliability? Do they have better anthennas ans more sonsitive detectors? Why do hobby pilots and boat captains always use Garmins?

UPD. We have a lot of ratheer simplistic answers aka "Garmin doesn't need cell coverage" or "Garmin has better maps" which is simply irrelevant since you can install any map on android as well (even official ones from Garmin) and use it offline. I'm sorry for formulating the question poorly, but I meant what are technical differences between phone GPS chip and standalone. Are they better (more accurate and fast) at getting location and how is it achieved.
gpt
If you already have a smart phone, then they can provide a lot of the same functionality as as GPS. If you don't, then GPS units are far cheaper. That said, a dedicated GPS unit has a number of benefits over a GPS app on a phone:

1. As a dedicated device, all of the battery in a GPS is powering a single thing. Thus the battery is likely to last longer than a phone which will have things running in the background and will be constantly draining power as you use it for other things.
2. ~~You can preload GPS units with maps of wherever you are going, which will then therefore work wherever you go. Phones, on the other hand, will have to download maps on the fly, which requires you to have cell phone service or wifi. So if you are in a place with no internet, the GPS on your phone won't do you much good because you won't have the corresponding maps to use it with.~~
3. Since there is little concern about needing the device to fit in a pocket, you can buy GPS devices that are larger and therefore easier to read and use.
4. GPS communication is one way. The device receives information, but doesn't upload anything unless you deliberately and manually do so. So if you are concerned about data privacy, a dedicated device is the way to go.