Welcome to the OP forum, Rudi!
I agree with most of what Pat's said. But another difference I see between the two pieces is that the greens in the vegetation and the orange hill are more saturated in the OP piece. Too often, the range of colors available in OP sets does tend toward highly saturated colors, particularly in the greens, but there are some alternatives available. Sennelier offers some nicer muted greens and other hues that more closely match the colors you've used in the SP painting (particularly in the OPs in their newer colors in the 200 numbers in their range).
Personally, I really prefer the texture in the OP piece- you created some nice loose impasto strokes in both the vegetation and sky. Also, I think that one thing that makes the soft pastel piece work better is that you included that round bush at the left side, which is missing in the OP piece.
I do think the SP painting is better than the OP one, for the reasons mentioned above, but I hope that you don't give up on your OPs based on this one experiment. If you're more accustomed to using SPs, it may take a little while to get used to OPs. I hope you'll continue to give them a try (one other big
advantage to consider: no dust!
), and post what you've been painting.