Let me summarize and add to the correct information given here on the various malts in question.
As Yooper Brew says, "dextrine malt" is a generic term for malts that increase final gravity, body and foam stability in beer. This is supposely done through the malts having a higher dextrine content which is questionable. Two examples of this are CaraPils, a Briess product and Carafoam, a Weyermann product. These malts are designed to add little flavor and color to the finished beer and mainly affect body and foam stability.
"Caramel malt" and "Crystal malt" are two terms that are often uses to refer to malts of higher color ( greater than 10 L) where the sugars have been caramelized. The British are more likely to use the term "crystal" as they produce carmelized malts that have a crystalline endosperm in the finished malt. To get this uniform crystalline endosperm, the carmelized malt must be produced in a roaster where the malt is moistened, stewed and then roasted and dried to get true carmelization and crytallinity. However, some "carmel" malts are made on a kiln by moistening the malt and attempting to get carmelization at high kiln temperatures. The problem with the kiln versus the roaster, the kiln has more air movement at high heat and only a small portion of the malt crystalizes. Most of the kernels of kilned carmel malts have a meally endosperms, like Munich malt. There is nothing wrong with this except it has a slightly different flavor from crystalline caramel malts made in a roaster.
So, even though the term "cara" is used in both "Carafoam" and "CaraPils", these dextrine malts should not be confused with caramel malts. Why have the maltsters used the term "Cara" in these products? It could be they use a roaster in producing these malts without the carmelization process, but I can not confirm this.
I hope this helps!!
Dr Malt