IIUC first proxy option highlighted with blue is same as using
-proxy in bitcoin.conf and second proxy option highlighted with blue is same as using
-onion in bitcoin.conf
What is the use of checkboxes in the middle highlighted with red?
These GUI features were introduced in PR4587, and they are available in Bitcoin Core since v0.12. The data in the red box on your screenshot are read-only, and they provide users with the actual proxy capabilities. Each checkbox has an appropriate descriptive tooltip. Also you could check out the
OptionsDialog::updateDefaultProxyNets() function in the source code.