Think of the iCloud library as one library that exist in the cloud. Setting aside the moment between when you turn it on and when all of the photos are uploaded for just a moment, each of your devices will have some mail of every image in the library as well as a larger version of the file.
On a device per device basis you can request the original sized file or let the system shrink, compress, optimize when storage runs low.
This design works well for people that just want to have one library and not several versions of the library. The point of iCloud photo library is if you have a 50 GB library total, you'll still end up with the same number of photos on each device even if the entire library size is 10 GB on an iPhone 30 GB on an iPad and 20 GB on your Mac.
The compression only kicks in once your space gets low on a specific device. I believe there are several settings of compression so that as you begin to fill up your storage with things other than the photo library, the images can continue to shrink up to the point where you have nothing left but thumbnails, presumably.
Well after an hour on the phone with Apple support, 2 phone restores and 1 iOS upgrade, we finally got to the bottom of this. Turns out the feature (to disable uploading of burst photos to PhotoStream) DOES work as intended. It's the wording of the feature description that is more than a little confusing.
The text below the feature states:
Only favorite Burst Photos will be uploaded to your Photo Stream
The trouble is, to me (and to the techs at Apple that I spoke to), that sounds like no part of a burst photo will be uploaded until you have chosen one of the photos in the burst, as a favorite. This is not so. What it actually means is that the entire burst will not be uploaded. But if you have Photo Stream turned on, a single photo from the burst WILL be uploaded. And unfortunately, it's not the first frame. I'm actually not sure what criteria iOS uses to decide which photo to upload, but it seems to be the first photo that it thinks is "the best" somehow.
So, the bottom line is that Photo Stream is an all-or-nothing proposition. Either every photo you take (including a single frame from any burst photos) will be uploaded, or nothing will be uploaded. There is no way to selectively upload photos on a case-by-case basis, unless you either leave Photo Stream off and manually share photos you want in your stream every time, or turn Photo Stream off & on between each photo you don't want to upload... but then you lose and have to re-download all your photostream content each time. Not a real great solution either way.
I feel Apple should re-word the description of this feature to make it more clear what the expected behavior actually is, but I won't hold my breath on that.
Best Answer
Connect your iPad to your Mac. Open iTunes, select the iPad on the top and on the left you will find a photos menu where you can select what you'd like to sync.
Alternatively, you can use iCloud Photos, which would have to be enabled on both your iMac and your iPad, which will then sync photos over the cloud (via your internet connection). However, if you have a lot of photos, you'd might have to buy additional space on iCloud.