Portable Air Conditioning
Most portable air conditioners are compromised by their design and are best chosen if no other alternative is available.
Remote Condenser
Some have a remote condenser which can be placed outside a window in the same way a split system works. In theory this is the best solution but in practice it can be awkward.
Ducted condenser
A ducted condenser blows conditioned air out a duct. This is less than ideal because you lose conditioned air while the duct also radiates heat back into the room.
Neither the remote condensor or ducted condensor are ideal as they have the compressor in the room, so they're far louder than a comparable split system. They are also more expensive to buy than a split although they do generally work out cheaper as they don't require professional installation.