I have a feeling that some people use these terms interchangeably, but support and uplift are not the same thing. And one doesn’t guarantee the other. Clearly, if you wear an H+ cup and are over the age of 25, chances are that any supporting bra is going to give you “some” uplift. Also, some bras are both supportive and uplifting. But very often, you’ll have to decide wether to give more importance to support or uplift based on the occasion. I perfectly get the appeal of amazing uplift, sometimes at the expense of support, in the boudoir or with certain types of outfits for instance. On the other hand, you might want to go for something really supportive when exercizing or if you have problems with back pain or more generally to preserve your boob shape and firmness.
Typically, full cup bras give good support, but not that much uplift. The same goes for most sports bras. On the opposite, push up bras give great uplift but not much support. Balconettes are somewhat of a happy medium.
While uplift is mainly determined by the shape and style of the cup and its seams (see Boobius Maximus’ article for more detail) with vertical seams giving more uplift than horizontal seams, support depends also on the fabric (with stiffer fabrics giving better support than stretchier fabric), the shape of the band (a band continuing under the cup gives more support), the width of the band (the more rows of hooks there are the more support you get), the presence of slings in soft cup bras or the presence of side panels in bras with underwires, the size and shape of the underwires… quite a number of things really! To make it simpler, I’ll give a you a few tried examples:
The Panache Tango is the typical great support, very little uplift bra: the power mesh, full coverage (it is supposedly a balconette but it comes higher than most) and sturdy underwires give this bra the supportive quality that made it a hit, but the configuration of the seams give very litlle uplift.
The Panache Harmony (discontinued but there are tons of it on ebay) gives pretty good uplift because of the sling created by its diagonal seam, but because it is more open than most D+ cup balconettes, you won’t get that much support on top and might end up with some jiggle if you have soft breasts.
Finally, Bravissimo’s Dotty spot is both super supportive and a heavy lifter due to its stiff fabric, diagonal seaming and fuller coverage than a standard balconette.