A computer network is a group of connected communicating devices such as Computers and Printers.
Local Area Network (LAN)
A local Area Network (LAN) is a computer network that connects computers and other devices in a limited geographical area such as college, university, office building etc.
internet (lower case letter)
An internet is two or more networks that can communicate with each other.
The Internet is collaboration of more than hundreds of thousands interconnected networks. The Internet allows communication and data sharing among hundreds of thousands interconnected networks.