Month to month storage units allow you to rent the storage unit on a month-to-month basis, without any long-term commitment. This gives you the flexibility to rent the unit for as long as you need it, and you can easily terminate the rental agreement whenever you want. On the other hand, contract storage units require you to sign a contract for a specific period of time, such as six months or a year. This means you are committed to renting the unit for that duration, and terminating the contract early may result in penalties or fees. The choice between month to month and contract storage units depends on your specific needs and preferences.