How to send a Apple iCal invitation from special eMail adress when I use iCloud
Your iCloud account (which is associated with your Apple ID) automatically sets up two calendars. One is called "Home" and the other called "Work". When you sent an invite from your iCloud "Work" calendar it will automatically use your Apple ID email address because that is the email account that is "hosting" the calendar. This can be confusing because it's the same email but two different calendars.

Gmail addresses (and most others), for example, come with calendars in the same way that iCloud does. In order to send invites from your work account, you will need to create a calendar with your work email address, and make sure that you select that calendar when you create an event. You should be able to make invites from that calendar and they should send from your work email address.