Whereas WhatsApp was bought in 2014 by Facebook (who have had several security breaches over the years), Signal is run by the non-profit Signal Foundation. While Facebook can’t access chats in WhatsApp, it does have access to the phone numbers, IP addresses, mobile network, length of time using the messenger, payment data, cookies, and location data of users. By contrast, the only information that Signal has access to is the amount of time that Signal has been install and the last date that it was installed.
WhatsApp is significantly more customizable than Signal, as it has had plenty of resources put into that department. It syncs your phone contacts, and users can form group chats, share locations and documents. They can also make international calls using WiFi. Signal allows for sending photos, videos, links, and other files but lacks chat rooms and additional customization that WhatsApp has. However, Signal’s beta version does include this, so it looks like a similar feature is coming.
Whether or not Signal will be able to overtake WhatsApp will be interesting to see. It might take some time or might never happen at all, but the field of communication apps has undoubtedly shaken.