What is the difference between public and private IP address?

A public IP address is the address that is assigned to a computing device to allow direct access over the Internet. A web server, email server and any server device directly accessible from the Internet are candidate for a public IP address. A public IP address is globally unique, and can only be assigned to an unique device.

where as a private IP address is the address space allocated by InterNIC to allow organizations to create their own private network. Computers, tablets and smartphones sitting behind your home, and the personal computers within an organizations are usually assigned private IP addresses.

Devices residing outside of your local network cannot directly communicate via the private IP address, but uses your router's public IP address to communicate. To allow direct access to a local device which is assigned a private IP address, a Network Address Translator (NAT) should be used.

• InterNIC is a registered service mark of the U.S. department of commerce. The use of the term is licensed to the Internet corporation for assigned names and numbers (ICANN) this helps you.

Hope this was helpful. 

public ip is that ip which is given by the service provider and we give its cost .public ip is used for WAN

private ip is used for LAN generate for own network

PUBLIC IP__Its used to configure devices world wide & being advertised globally as unique IP.

Private IP___its not unique IP & being used after configuration of NAT or PAT for globally identity.

Any one can use private IP without purchasing for personal LAN while Public IP need to be registered before configuring in any LAN  

Public IP is Like your Home address!  Privet IP is more like your rooms at your home with individual numbers marked for the identification purpose.   

Just as your network's public IP address is issued by your ISP, your router issues private (or internal) IP addresses to each network device inside your network. This provides unique identification for devices that are within your home network, such as your computer, your Slingbox, and so on.

Private IP is used locally which is actually NATed public IP, while public IP is provided by ISP which can be connected to Internet.

The Public IP is :An internet protocol address   which assigned to each device participating in a computer network that uses the internet protocol  .example :45.246.96.224the private IP is :An Internet Protocol address  which assigned to each device participating in Local area network example :192.168.1.10

Public Ip address provided by the isp to acess globally , the private ip address to be used in your own network E.g router

public ip : is that ip by which we are able to communicate with out side of the world via internet . 

private ip : is that which makes us able to communicate with in a lan 

Private IP Addresses are only IPs used in local networks for homes and offices and they are not allocated to any specific organization, thus they can’t be used to access the internet.

A public IP address is a unique IP and not repeated all over the world and it can be used over the Internet. Any device or network must use a public IP address in order to access the internet by assigning the proper public IP address to it or to the modem used for NATing.

Public IP's are those IP's which are routable on internet while public Ip's are not routable on internet they are used internally.We can not reuse public ips because it is assigned by IANA and it is globally unique