I have tried using both ,what ever I do, I don't find the difference between the two features, please help with example and a application
Difference between boundary and loft is that there are more options for setting up boundary features in term of the geometrical layout of profiles and guide curves. A second major difference is that there is no such thing in boundary as profile and guide curves.
With loft you must have a profile at the beginning and end of the feature.
With boundary you can lay out the profile sketch planes like X.
Loft is based on two different types of curves, the profiles and the guide curves. It weights how closely it follows them differently. Boundary has only one type of curve, but in two directions, and weights the two directions equally. Boundary is newer and tends, overall to give you nicer surfaces. Boundary gives you more control over the curvature at the edges. You can force tangency or curvature continuity to existing surfaces on all four edges. Loft has more quirks, but is useful for certain cases, which I can't recall right now, except one, the centerline loft.