... this looks to me the most common morning glory Ipomoea cairica, commonly known as railway creeper or ivy-leaved morning glory and lesser known names are: Cairo morning glory, messina creeper.
Your query: Is there an easy way of distinguishing Ipomea from Argeyria?
My own perception: Argeyrias have stouter base, shorter throats, thicker (hairy) sepals ... all this that I have observed in one species A. nervosa !! .. so may not hold true for all Argyreias
For laymen like me, a funny (and practical point of view) is that we must be fortunate enough of getting to see as many species regularly.