WhatsApp has its own emoji designs which are displayed on all WhatsApp platforms (except WhatsApp for iOS which uses Apple's native emoji set).
Prior to WhatsApp creating its own emojis, Apple emoji images were used by WhatsApp on all platforms including Android and the web. WhatsApp released its own emoji set in 2017 and ceased using Apple emojis on all non-Apple platforms.
One emoji supported by WhatsApp but no other platform is the Texas Flag emoji. This is a valid subdivision flag supported by Unicode, but not listed within any Unicode emoji release and as of 2019 is not supported by any other major vendor.
Emojis from WhatsApp 2.19.62 are displayed below.