Having an in-unit washer and dryer means you have access to laundry in your apartment.
These are only available
for you to use within
your unit rather than for other people in the building.
You don't have to worry about finding a washer and dryer to go to the unit because it will already be there once you move in.
When you're living with in-unit laundry, the biggest advantage is that you can get your laundry done right away whenever you want.
You will also
not have to bear the huge costs associated with this type of facility. The cost will be automatically included in your fare.
If you have
an in-unit laundry set up, you can usually do as long as you want, as long as your machines are not loud.
You have all the facilities of in-unit laundry, but there is also a short commute to and from the machines.
versus washer-dryer connections, you need to consider the fact that you'll need to find the appliances to connect yourself.
means they're already provided to you while having a hookup means you'll have to locate the washer and dryer to get in.