1- Signal is a messenger app which provides messaging services similar to what Whatsapp does.

2- Signal App is developed by Signal Foundation and Signal Messenger LLC which is a Non Profit company. WhatsApp co founder Brian Acton has created Signal Foundation. ( As the Brian has invested $50 Million dollars, and as of now the company is NON PROFIT, you can expect that data monetisation will not happen soon)

3- Signal is available for iPhone, iPad, Android, Windows, Mac and Linux. This App is free and can be download from respective stores.

4- It has following features, as same as WhatsApp

• Text message
• Media File Sending option - Video , Image
• Document Sending option
• Video call
• Audio Call
• Group Video Call
• Link Sharing

5- Like WhatsApp , Signal can also be used on Laptop, Computers and Tablets. The only difference is, as there is no cloud back up, previous chat history will not appear on the new device you start using.
Example - If you are using Signal on your phone 5 days, and then wish to use it on Laptop as well, then the chat for last 5 days will not appear on the laptop, though you will have access to the same on phone.

6- Signal does not provide cloud based CHAT BACKUP system like WhatsApp. All the backup will be stored on your LOCAL DEVICE, which is your Phone. In case you change your phone, then you can download the back up from the old phone and upload it on your new phone. But in case you loose your phone, then you LOOSE your SIGNAL BACK UP as well. ( This could be preity scary as well, if your phone gets into wrong hands, your data might get used in in appropriate ways)

7- Signal Groups - Something New and stands to their tag line "Say Hello to Privacy" Signal allows you to create groups and add upto 150 members ( WhatsApp has 250+), but the catch here is that, any member added to any group will get an invite to get added, if he/she accepts the invitation, then only the person will get added to the group. ( What relief from getting added to Annoying Groups).
Like WhatsApp Signal also provides, Disappearing messages in groups and also has, option to delete the messages in the group.

8- Coming to the PRIVACY part of this APP. So Signal takes only one type of DATA from the user, CONTACT DETAIL, which is your phone number. Apart from that no other data is taken from the user. All conversations on Signal are end-to-end encrypted, meaning no third-party, nor Signal can access them.

Apart from this information SIGNAL also

• stores some additional technical information on its servers, which includes "randomly generated authentication tokens, keys, push tokens, and other material that is necessary to establish calls and transmit messages."
• it does queue "end-to-end encrypted messages on its servers for delivery to devices that are temporarily offline.
• it can "optionally discover which contacts in your address book are Signal users."
• it may share some information with third parties to provide some services. For example, instance third-party services, which provide the verification code. It also notes that if a user relies on third-Party Services like "YouTube, Spotify, Giphy, etc. in connection with our Services, their Terms and Privacy Policies govern your use of those services."

9- Lastly as of now there is SIGNAL for business as Separate app or Function. Still business can use SIGNAL app by creating a regular account .

Functions	SIGNAL	WhatsAPP
All Media File and Document Sending option	Available	Available
Audio and Video Call	Available	Available
Data Accessed	Contact Number	According to the App Store, WhatsApp reserves the right to collect :purchases, financial information, location, contacts, user content, identifiers, usage data and diagnostics.
BackUp Mode	Local backUp Only	Cloud and Third Party Back up.
Platforms Available on	Android, iOS, Windows,Linux	Android, iOS,
Groups	150 Members, with Invitation to get admitted, NO AUTO ADMIT	250+ Members
Business	No Separate Account / No Separate App	Separate App
DownLoad Link	SIGNAL	WHATSAPP

Note - All information is Collected from Secondary research only.