A dryer label carries more information than the capacity figure on the front. Two dryers that look alike on the floor can differ in how they vent, how they dry, how they are cleaned, and what they need from the room around them. Compare those points on paper before you compare looks.
Start with fit. Measure the space behind the unit, the depth with the vent connected, and the door swing in your room. Check the vent type the model uses and the length of vent it can handle. Then confirm the fuel and outlet. A gas dryer and an electric dryer need different hookups, so you can compare only within the fuel your home already supplies. If the unit needs a specific outlet, note it before you compare anything else.
Drum capacity is stated by the maker as a volume. It is a useful figure, but it does not tell you how much of a particular load will fit. Compare it with how you actually load. A larger drum helps with bedding, but it still needs the same clearance and the same vent path, so the capacity figure cannot stand alone.
Next, look at the drying method. Vented models push moist air outside. Condensing models collect or drain water, so check where that water goes. Heat pump models use different airflow and have their own cleaning and service needs. Read the manual for what must be cleaned, what the owner can clean, and what needs a trade. A model that asks for more upkeep is not wrong for your home, but you should know the schedule before you buy.
Look at the controls. A moisture sensor cycle and a timed cycle work differently, and the manual should say how the sensor is cleaned. Ask the seller to show you the cycle options on the unit, not just the list printed on the label.
Check any energy or efficiency rating on the label and find out what program or test it came from. Ratings from different tests are not directly comparable. Compare only within the same rating basis, and treat the label as a starting point rather than a verdict.
Then read the warranty line. Find out what it covers for parts and labor, what registration step it requires, and who services the unit in your area. Write down the model and serial numbers from the label and keep them with the paper. Those numbers tie the paper to the machine.
A simple comparison grid helps. Put vent type, fuel, drying method, cleaning requirement, control options, and warranty terms in columns, and fill each row from the labels and the paper. Hold off on brand names until the grid is full, so the layout decides the comparison rather than familiarity.
For how long a dryer tends to last and how to plan around its age, see the clothes dryer page.