WhatsApp primarily uses Apple emoji images for emoji support on all platforms, including Android. This differs from most apps which use the native emojis available for each platform.
A few emojis appear differently in WhatsApp to other platforms. The red heart emoji (offically known as heavy black heart) has a beating animation, and appears larger than the other emojis when sent in a WhatsApp message:
WhatsApp for Android uses custom artwork for the middle finger emoji which was added in 2015 prior to Apple including this emoji.
Emojis from WhatsApp 2.16 are displayed below.