When I first learned about pico de gallo twenty-some years ago in San Antonio, it was a sauce based on black olives, with plenty of garlic and serrano peppers in it - not like a tomato salsa. But a recipe for celebrating Cinco de Mayo in National Geographic Kids lists the ingredients as tomatoes, onion, jalapenos, cilantro, lime juice, and salt, which looks just like a salsa fresca to me. According to Wikipedia, pico de gallo is similar to a salsa but has less liquid; it notes that "In many regions of Mexico the term 'pico de gallo' refers to any of a variety of salads, condiments or fillings made with sweet fruits, tomatoes, tomatillos, or mild chilies, not necessarily with hot chilies or any chilies at all." So apparently I learned an idiosyncratic version using black olives as the "fruit"; I've never seen one like it anywhere else.
A pico de gallo recipe from the Jalapeno Cafe looks worth trying:
1 medium jicama, pared and cut into 1/2 chunks
3 oranges, peeled and sectioned
1/3 cup chopped onion
Juice of one lime
1 teaspoon salt
1 teaspoon chili powder
Mix jicama, oranges, onion, lime juice and salt in bowl. Let stand in refrigerator at least one hour before serving. When ready to serve, sprinkle with the chili powder.