Form 1065 is used by partnerships, including multi-member LLCs taxed as partnerships, to report income, deductions, gains, and losses to the IRS. Partnerships do not pay federal income tax at the entity level; instead, income and losses pass through to the partners, who report them on their individual tax returns.
Form 1040 is the form used to report income to the IRS, claim tax deductions and credits, and calculate their tax refund or tax bill for the year. The IRS releases a revised version of the form for each tax filing year.