I think it's important to look at a few terms. "Manual therapy" is an umbrella term which can mean anything done manually; very broad. "Manipulation" can also be interpreted a couple of different ways and sort of envelops "mobilization" as well. However, when reading the literature, "manipulation" usually refers to HVLA. In that regard, HVLA is HVLA whether it's a DC, a PT or a DO performing it. There are of course many different techniques and maneuvers within the HVLA category, but they all share the commonality of using a high velocity, low amplitude thrust from which there is often a "pop" or "crack" sound produced. The thrust takes the joint beyond the active and passive ROMs into the 'paraphysiologic zone' as it's been described but never beyond the 'limits of anatomical integrity' (i.e., you aren't damaging anything). So again, it doesn't matter who is performing the thrust, it's still manipulation (or more specifically, HVLA manipulation).
With chiros, there has historically been less standardization when it comes to treatment than is seen in the PT world. This is both a blessing and a curse. The blessing is that a DC conceivably has more options/techniques at his/her disposal; whether they have all been researched per se is a different matter. The other positive aspect to the heterogenicity of chiropractic is that if one chiro doesn't help you, you could really go down the street to another chiro and have a completely different experience (this is sort of true for PT but perhaps less so). The curse is that, these days, there is more emphasis on standardization and proving efficacy, therefore having each individual chiro doing different things for the same patient can be seen in a negative light. If the prediction rules end up working out, I think we'll see movement in that direction from the chiro profession.
