Renny is correct - the main difference between alcohol and oil is the rate of diffusion and the subsequent shift in how effects accumulate. Using alcohol as a base will result in a much more rapid diffusion rate that results in reaching maximum effect in a short period of time. While this may be useful at times, there may be more of a “shock” effect that can lead to OD situations. Also, spraying is an uneven art, with applications varying from spray to spray for both dosage and angle/direction/area of application, so there is a bit of uncertainty added in for the effects.
With oil as a base, the diffusion rate is slower but more controlled and steady over time, and more importantly, the effects are more subtle, smooth, and “mellow” as Jasmin mentioned. This helps to prevent the “shock” effect by allowing exposure effects to accumulate over time, building up the longer the exposure period is. In some instances, this is more desireable since it’s more of a gradual buildup that feels more natural on the distractant’s part. This is why Raw Power can be used at 10 mcg/drop of Androstenone and not OD as easily as 4 sprays of TUTH. Since oils are usually deployed by a dropper, the applications are more consistent. The drawback with oil is that the effects are slower and more time consuming to apply than sprays, and there are occasions when you do want that “shock” effect when things are going too slow 