I came across this interesting paper prepared under DFID's Research for Development initiative.
It gives an anthropological perspective on aid as a 'gift relationship' with a gift being defined as a 'material expression of a social relationship'. It can be divided and analysed in four components, the object that is given, the chain of relationships through which the gift passes, the motives of those involved and the rules or principles governing their behaviour
Viewed from this perspective, can we see a difference between the different aid modalities? Can project aid signify a different kind of relationship than direct budget support? It's certainly difficult to put a big sign over budget support saying 'Gift from the people of...'
The paper lumps the different aid modalities together, so it is mute on this point.