Bruschetta: Technically pronounced broo-skeht-uh, but Americanized it’s bruh-sheht-uh; Toasted bread topped with meat and/or cheese and/or veggies, most commonly tomatoes and basil; Italian.
In its beginnings bruschetta was specifically toasted bread rubbed with garlic with a drizzle of olive oil and MAYBE toppings, so technically that is what bruschetta “means” but present day, most Americans are referring to the bread plus the topping. Garlic is still usually a part of the toppings since it’s still Italian, for goodness sake, OBVS some garlic up in there…
Crostini: Pronounced crust-ee-nee; Toasted bread, usually baguette, topped with meat and/or cheese and/or veggies; Italian.
See the similarities??? Crostini does not really have a specific traditional topping, so it is more varied. Basically the other difference is that the bread is usually smaller than bruschetta, a baguette rather than a thicker and wider piece of Italian bread. Some people deconstruct it a bit and use the toast piece to dip in hummus or other appetizer-style dips, kind of like bagel chips.
Either way you have two appetizers that are both quite easy to make, especially bruschetta if you are able to chop tomatoes and put the oven on broil, no?