There are several plant varieties that are referred to as "hens and chicks." Sometimes it is difficult to tell them apart. Sempervivum and Jovibarba plants for example look almost identical, but their flowers are completely distinct. Botanists actually use a plants flowers more than the plant itself to distinguish/classify plants. See the difference in flowers below.
The Jovibarba succulent flower is generally yellowish with closed petals.
Sempervivum on the other hand have an open, star shape flower that can range from pink to white or yellow.