Yellow Pear is a specific breed of heirloom tomato from the eighteen hundreds or so. It is not merely a shape and color of tomato. There are many yellow, pear-shaped tomatoes, but only one is Yellow Pear (capitalized, since it's a proper noun).
However, the term is sometimes used to describe any yellow, pear-shaped tomato, but I recommend you avoid this! It's confusing, and ambiguous. Always capitalize it when you mean the breed.
Similarly, Red Pear is also a breed name. Same for Green Pear, and Chocolate Pear.
Here are some breed names of some other yellow, pear-shaped tomatoes:
* Yellow Trifele
* Beam's Yellow Pear
* Medovaya Kaplya
There are plenty of others. They are not the same as each other.