There’s a discrepancy in terms of number active of numbers, because WhatsApp has 800 million, with 500 million more than Telegram, but the latter application came much later, in 2013, four years after the release of WhatsApp. They are very different from one another, although both of them allow their users to send text messages, or photos, videos and audio files.
Both applications are supported by multiple platforms, but only Telegram can be installed on computers running on Windows, OS X or Linux, while WhatsApp has a web feature which runs with one of these browsers: Firefox, Opera or Chrome. Also, to register on any of these applications, you will use your phone number to get verified and you will receive a SMS text containing the authorization code. When changing the device, the users can restore their chats they’ve backed up previously. However, when logging into Telegram, the IP address and time of login are memorized and the users are notified to the initial device.
Since both applications allow sending multimedia files, the maximum upload file size on WhatsApp is 16MB, while Telegram allows uploading files of up to 1.5GB. However, while the messages on WhatsApp are stored on the users’ devices, on Telegram, the messages are encrypted end-to-end and self-destructing after the receipt reads them. The users can set messages to be automatically deleted at pre-set time intervals between 5 and 10 seconds after their friends open them, but that doesn’t mean that they can’t take a screenshot of the message and use it later as a proof that the sender said something embarrassing, or told a dark secret.
Another thing that both WhatsApp and Telegram have in common is that the messages can be sent only to other people who are using the same application. In addition, both applications allow creating group chats, but on WhatsApp can be invited only 100 members, while Telegrams allows twice this number.
Unfortunately, Telegram doesn’t support voice calling, so if you want to talk to your loved ones for free, using only the internet connection (3G or WiFi), then you will need to install WhatsApp. However, after one year of free use, an annual fee of 0.99 dollars will be applied.