As nouns, they usually mean the same thing. "What's on the agenda for today" and "What's on the schedule for today" would both mean the same thing. But "schedule" can be a verb too, and agenda can't. So I can say, "I will schedule an appointment for you at 10:00a.m." Or "I'm going to schedule this task for next week."

This is an example of a schedule: COMMUTER RAIL TRAIN #790 Forge Park/​495 station 04:55 am Franklin station 05:02 am Norfolk station 05:08 am Walpole station 05:15 am This is an example of an agenda: BOARD OF SELECTMEN'S MEETING 1. Call to Order 2. Pledge of Allegiance 3. Unanticipated 4. Announcements & Recognitions 5. Minutes 6. Warrants: Vote to authorize Chairman, or his designee, to sign Warrant(s) for weeks ending 1/13/18 7. New Business: a. Announcement – Wayne Perkins b. Vote to approve a 2nd Hand Dealer’s License for Kelly Shumway for TKO Restoration & Treasures to be located at the Antique Co-Op at 40 North Main Street c. Vote to send to the Planning Board the proposed “Solar By-Law” so that they may hold a hearing on the change and report back to the Board for the upcoming Town Meeting. 8. Hearings, Meetings & Licenses: Variance Request for 14 Lakeview Terrace 9. Oliver Estate Items 10. Town Manager’s Report 11. Report on Committees, Commissions, Boards 12. Correspondence 13. Adjourn

In my experience "agenda" is much more European. I don't hear many people talk about their "agenda" in the U.S. but instead it is much more common to say "schedule".

In the US a "schedule" is usually a timetable. It is not only a list of things that are going to happen, it is a list of the times at which they will happen. The "train schedule" says that a train will arrive at Union Station at 6:13 p.m. Very often, it is an hour-by-hour or minute-by-minute list. "I can schedule your appointment for Thursday" means "I actually have specific times available on Thursday." You can be put on the schedule for 10:30 am or 2:15 pm, perhaps. A schedule can be less definite than that, but the meaning usually includes the idea of time. Incidentally, in the U.S. we pronounce the first syllable as "sked-" while the British pronounce it as "shed-." (In both cases, some speakers pronounce the second syllable as "-zhəl" and others as "-yool.") In the US "agenda" is usually a formal plan for a meeting. It is the list of items to be discussed, or decisions to be made. In a formal meeting, there will be a process for getting an item on the agenda. At the meeting, the chair takes the items on the agenda in order. Often, each item will be discussed for however long is necessary to reach a decision. There is no timetable. Perhaps the meeting starts at 7 pm. You care about the third item on the agenda. But you do not know when it will be discussed. The meeting might go quickly and your item might come up at 7:30. It might not be until 9:00. The first two items might take so long that your item won't be discussed at all.