As a windows user used to managing this by yourself, iPhoto can be a little bit confusing. I've been using Albums and not events so far. What's the difference? The events are confusing with the iPhone photo stream.
It's not really a 'Mac' vs 'Windows' difference. It's that iPhoto is a Digital Asset Manager (DAM), like Aperture (another Mac only application) and Adobe's Lightroom - which is both Mac and Windows. However, iPhoto is designed for the masses, while Lightroom is intended for very serious and professional market. And priced accordingly.
What is important to know about a DAM is that there are two parts: Your photos, and the database. In a DAM (like iPhoto) the original photo is never altered by the application - the original image is always available in case you need to go back the beginning. Everything the application does to that photo is merely recorded to the database. Easy enough to understand when thinking about keywords, titles, ratings, etc. But this also applies to Albums, Smart Albums, Events etc. The photo is not actually moved or copied (even if you 'duplicate' within iPhoto).... the application simply notes that the photo appears in the following places. When you duplicate the photo (within iPhoto) it also merely notes that in the database. So you can have many 'copies' of an image (with variations of cropping and editing) without using up more disk space.
An "Event" is sorta like a roll film. It is all the photos you took in day, or at a party. There are different settings you can have to sort the photos, but generally (more or less) it is a single import (if you import your images after going somewhere). You can merge two (or more) events into one (you changed memory cards during the office party - iPhoto would see each card as an event - so you merge them back into one 'Party' event). Or you can split events... The party while the boss was there, and the party after management left
Essentially, and event is a grouping of images that iPhoto has decided belong to a single time-period or activity.
An Album is a grouping of images that you put together based on your own criteria. Often, the images may be the same as an event. A day trip out to have a picnic at a winery. But often an Album is either more selective. Perhaps only the best images from an event. Or an Album includes images from multiple events. An album can have images of your cat from when she was a kitten. An album can also be a work space.... for instance you are putting together all of your best sunset photos which you will then use to create a calendar. But the essence is that you have decided which photos go in an album, and in what order they appear.
Crucially, an image can appear in as many albums as you want. So, if you have a photo of your friend at the office party, that image can appear in both the "Friend" album and the "Office Party" album. Any edits you make to one image will be reflected in both images (unless you use iPhoto to duplicate the image first - perhaps you need to crop it differently.)
Smart Albums can really harness the power of the database.
Also one other thing, I changed a photo in iPhoto, edited away some unvanted lens flare on a pic. Then I uploaded this to facebook via the facebook webpage, and the change i did wasn't reflected in the pic? What does actually iPhoto do with changes to photos?
I suspect you uploaded the photo directly from the Finder, or using the FB upload interface. Go back to the beginning of my explanation.... iPhoto never alters the original file (non-destructive editing). To get your 'edited' photo you have to use iPhoto to 'share' or 'export' the image. It is during this stage that iPhoto (or any DAM) creates a new photo by applying the changes it has recorded in the database. If you just upload the image (via FB or other direct file browsing) all you are doing is uploading original file, as it came out of the camera.
DAMs start with the assumption that you will only work with your images through their interface. When you bypass the DAM's interface you get weird results, lost images, and in a worse case scenario a corrupted database (though that is really really tough to do... they are built to be robust).
My advice... let iPhoto suck your images into itself, and then let it do the hard work. Anyone who is touching their images outside of iPhoto, whether during the import stage or otherwise, is - imho - probably making life more difficult for themselves and working harder than they have to. Spend some time getting your head around how a database system worked. Once you do... you will most likely wonder why you took so long to start using it.
