Difference between Google Voice and Google Duo

1. Google Voice :
Google Voice is a telephone service that provides the call forwarding services and voicemail services. It allows users to have a single number and forward it to multiple phones. It was launched by Google in 2009. It is available for web, android and iOS systems. It enables to retain the phone number despite changing the phone device. It uses the contacts across the gmail of the user. It provides many services such as voicemail, free text messaging, call history, call screening, blocking of unwanted calls and voice transcription to text of voicemail messages.

2. Google Duo :
Google Duo is a video calling mobile application which is available for Android and iOS operating systems. It can also be used through Chrome web browser on personal computers. It enables users for high quality video calling service. It is developed in such a way that it works properly even id user is having slow internet service. There is end-to-end encryption that enables the high security. It also enables group video calling. Earlier it had group size of 8 but later it was extended to 12. It was launched by Google LLC. It was launched in 2016.

Difference between Google Voice and Google Duo :

GOOGLE VOICE	GOOGLE DUO
It is a telephone service that provides call forwarding and voicemail services.	It is a video chat application that provides video calling services.
It was launched in 2009.	It was launched in 2016.
It offers messaging and voice calls.	It offers messaging, voice calls and video calls.
It offers text messaging.	It recently added service for recorded messaging but does not offer text messaging.
It is mainly used for making voice calls.	It is mainly used for making video calls.
It does not require to have gmail signing.	It requires to have gmail signing.
It provides services like call forwarding and voicemail.	It does not provide such services.
It has less number of users.	It has comparatively more number of users.
It does not provide services for group creation.	It provides services for group creation.
Only 2 people can be involved in calls.	Up to 12 people can be involved in calls.