Deciding which shrimp is male or female is sometimes difficult because at first glance they look so similar. However there are some useful clues we can use.
For example, a male will have a straighter belly area and longer antennas. A female will have a curved underbelly area for carrying the eggs and will have shorter antennas. Females will also have what looks like a horse saddle around their head area. Those are undeveloped eggs. This will usually look like a dark area, or yellow on more translucent shrimp.
This image by Shrimp Corner UK is a good example of male vs female: