What is the difference to control multiple devices by adding 2 devices on project or using bridge?

What is the difference to control multiple devices by adding 2 devices on project or using bridge?
Is there any proposes to use at different condition?

Bridge is used to control one device from another, or to transfer data between devices.

Say you have a NodeMCU in your living room with a temperature sensor attached, and another in a cupboard which controls a central heating valve. You would use Bridge to send temperature data from your living room device to your controller device.

If you put both devices in one project on the app then you could display the temperature readings, and see/change the status of your heating controller from the app.

Using Bridge allows the devices to talk to each other via the Blynk server, independent of the app.

Pete.