Contract Aligned: means the billing is aligned with the CONTRACT start date, so if the contract start = 3/1/17 & it's quarterly billed, the quarterly billing will reflect: 3/1/17-5/31/17, 6/1/17-8/31/17.9/1/17-11/31/17 and no on. Note: Quarters are aligned to the contract dates.
Calendar Aligned: meaning billing is aligned to the Calendar months, so if Contract start date = 3/1/2017 & it's quarterly billed, first invoice will be partial (3/1/17-3/31/17) and the remaining quarters will align with Calendar quarters and be for 4/1/2017-6/30/17, 7/1/17 - 9/30/17, 10/1/17-12/31/17 and etc.
Annual billed contracts should be aligned to the contract so the customer gets a 12 month invoice. If an annual billed contract is aligned to the calendar, customers could receive 2 invoices. Example Calendar alignment with annual billing, 3/1/17 - 12/31/17 and 1/1/18 -2/28/18.