Each contract is classified into a tier using its delta - a measure of how sensitive the option's price is to a move in the stock. In simpler terms, delta tells us how closely the option tracks the stock and gives us a reliable proxy for how likely the option is to be profitable at expiry.
Contracts with a higher delta (closer to 1.0) move more in line with the stock and are more likely to end up profitable - these become the Low risk tier. Contracts with a lower delta are more sensitive to bigger moves and less likely to pay off - these become the Aggressive tier. Balanced sits in between.
You never see delta in Easy Options. It works in the background to make sure the three tiers you are shown always represent meaningfully different risk and reward profiles, not arbitrary labels.