Is MobX a framework?

Not in the sense of a JavaScript Framework. Frameworks may leverage MobX.

From my answer in Quora:

https://www.quora.com/Is-MobX-a-framework/answer/Jayaram-Krishnaswamy

From MobX site:

MobX is a battle-tested library that makes state management simple and scalable by transparently applying functional reactive programming (TFRP). The philosophy behind MobX is very simple:

Anything that can be derived from the application state, should be derived. Automatically.

which includes the UI, data serialization, server communication, etc.

https://mobx.js.org/README.html

What is the difference between NFC and Bluetooth?

Near Field Communication (NFC) is a standards-based short-range wireless connectivity technology that makes life easier and more convenient for consumers around the world by making it simpler to make transactions, exchange digital content, and connect electronic devices with a touch.

More on their differences here;
http://nearfieldcommunication.org/bluetooth.html

Both use wireless communication.

Bluetooth is short-range with a maximum range of about 30 feet
NFC (Near Field Communication is even shorter with a range of few centimeters (like NFC card to enter your hotel room).

NFC consumes less power compared to Bluetooth.

Because of the range, Bluetooth is more prone to interference with other Bluetooth devices.

Note that the newer Bluetooth known as BLE (low energy type) may use energy comparable to NFC