What I found was that words written in katakana are often closely related to their english translations. A few examples include but aren't limited to how "daburu" is Japanese for double, "gurasu" is Japanese for glass, and "toire" is Japanese for toilet. That is the main difference between times when hiragana is used and times when katakana is used. These are often referred to as "loan words," and they are written in katakana to show that they aren't of Japanese origin. In other words, they come from other countries, hence why they are called "loan" words. I also found animal words such as "panda" and "hamasuta," which translate to panda and hamster respectively. Again, they are written in katakana to signal foreign origin.
