Can a fluid ounce be equivalent to an ounce?

There is no such thing as a regular ounce. A fluid ounce is a unit of volume. There are 16 fluid ounces (US) to the pint (US). A dry ounce is a unit of weight. There are 16 dry ounces to the pound. Frequently, the Words fluid and dry are omitted. You have to know whether you're talking about volume or dry weight.