The question of the original poster is actually a straight forward one, presuming the accuracy of the vocabulary you are using. The dispensation would not be invalidated in the circumstance you present and, yes, you are in essence confusing two concepts, and precisely in the way that you articulate.
A private vow can be dispensed by one who has the faculty to do so. The grant of a dispensation from a private vow is governed by Canon 1196. If the ecclesiastical authority who has the power to do so has granted a dispensation, then the dispensation is effective and the vow is no longer binding on the person who made it.
Beyond that, a person should not lightly make a private vow and doing so without noting the gravity – with the thought that one can, after all, be dispensed – could (and I stress could…I cannot make that determination from what you have said) be something that should at least be mentioned in confession. That, however, is dependent on matters not articulated in your post and so would best be resolved, I suggest, by a confessor in the sacrament of penance now that the vow has been dispensed.
To the other poster: vows and oaths are different matters. Vows are covered by Canons 1191-1198 and oaths by Canons 1199-1204. The various circumstances you relate, such as whether or not a private vow was made in the presence of a priest, do not alter either the nature of the vow or an ecclesiastical authority’s ability to dispense which, again, is well and simply explained by the aforementioned canons themselves. I have no idea what the question “Then, is the vow maker going on to make a consecrated vow?” means unless you are attempting to quote Canon 1198: “Vows taken before religious profession are suspended as long as the person who made the vow remains in the religious institute.”
The canons may be consulted using the link below. I hope this information helps.