All three phones run on Qualcomm's latest Snapdragon 855 chip, but they differ in RAM and storage options.
Galaxy S10e: 6GB RAM/128. Option for 8GB RAM/256GB storage
Galaxy S10: 8GB RAM/128, 512GB storage
Galaxy S10 Plus: 8GB/128, 512GB storage. Option for 12GB RAM/1 TB (1,000GB) storage