Are electrolytes similar to salts and cause water retention?

Yes: Electrolytes are the collective name for sodium, potassium, chloride, etc. -- the chemicals that make up the liquid part of blood. Too much of one particular electrolyte -- sodium -- one component of nacl, or salt -- can cause swelling. Most energy drinks have "some" electrolytes in them, and drinking too much of them can contribute to swelling.

Yes: The most common "electrolyte" is salt. Some salts of other elements such as potassium are usually present. Many people retain water, experience swollen ankles, and feel bloated after too much salt consumption.