♥ U+2665 BLACK HEART SUIT is the card-suit heart and the one produced by the HTML entity ♥. ❤ U+2764 HEAVY BLACK HEART is the Dingbats heart; on its own it usually shows as text, and followed by U+FE0F it becomes the red heart emoji ❤️.
The coloured hearts (💙 💚 💛 🧡 💜 🖤 🤍 🤎 🩷 🩵 🩶) are separate codepoints. Some popular hearts are not single characters at all: ❤️🔥 “heart on fire” and ❤️🩹 “mending heart” are sequences joined with a zero width joiner, so they must be copied as a whole. See emoji ZWJ sequences.
Click any symbol to copy it. Names link to the full character page with every encoding.