You can use Telegram on any device you want at same time. PC, Phone, tablet, you name it. WhatsApp on the other hand only works in one device (your phone). The

You can use Telegram on any device you want at same time. PC, Phone, tablet, you name it. WhatsApp on the other hand only works in one device (your phone). They released a webchat, that just works as a proxy to connect to your phone. So in order to use the WhatsApp web, you need your phone on and with internet connection.