The difference between fiducia and confidentia


What is the difference between fiducia and confidentia in these sentences, particularly the bolded one? I posted the previous sentences for context. Feel free to critique my translation, which I know is probably not very good.

Sensus enim hujus loci est (Romans 10:9), Si Jesum Christum, qui obedientibus sibi aeternam faelicitatem a Deo Patre suo decretam ac destinatam esse docuit, ex mortuis excitatum, & sic veracem ea in re a Deo ipso comprobatum esse, proinde firmiter certoque eiusmodi faelicitatem a te sperari, cumque enim fiducia ac πληροφορία exspectari posse credideris, si ei obedias, salvus eris: quia fieri non poterit scilicet, ut non obedias Christo isti, id est, doctrinae eius, quam Deus tam illustri actu sibi probari gratamque esse demonstravit. Fiducia tamen haec, confidentia potius est voluntaria, quam fiducia, quae propria est iis, qui jam ista confidentia fulti, doctrinae Christi obtemperant. Haec enim potius est necessarium aliquod obedientiae consequens quam actus obedientiae voluntarius, qui nobis mandatur passim. Istius fiduciae, tanquam a fide distinctae, mentio fit ad Ephes 3.12.
This is what I have:

The sense of this place is that: If you believe that Jesus Christ, who taught that eternal happiness has been decreed and destined by God His Father for those who obey Him, and was proven truthful in the matter by God himself having been risen from the grave, and if you believe that, accordingly, such happiness can be firmly and certainly hope for by you, and expected with all confidence and assurance, if you obey Him, you will be saved: because it is impossible, that you do not obey Christ, that is, his doctrine, which God by an illustrious act has demonstrated to be pleasing to Himself. Yet this boldness is a voluntary confidence rather than boldness, which is proper to those who are submitting to the doctrine of Christ having already been supported by that confidence. This is rather a necessary consequence of obedience than a voluntary act of obedience, which is everywhere consigned to us. Mention is made of that boldness as distinct from faith in Ephesians 3:12