To clarify - HX Effects and HX Stomp are quite different products (as has been covered all over the web) aimed at different areas of the market. HX Effects has more cumulative screen realestate, nearly 3x the number of footswitches, more flexible I/O, is a much more comprehensive MIDI command centre in terms of the kinds of messages it can send and isn’t limited to a fixed number of blocks.
For musicians not bothered by the pedal’s dimensions who require the above but have zero need for amp/cab models, AUX input, a headphone amp or another audio interface, HX Effects is a more appropriate purchase. It isn’t as simple as “Stomp is a better version”
Re: pricing, Line 6 intended for them to be the same price - and they are in the US - but obviously some price dropping/matching has happened between retailers over here hence HX Effects now being cheaper.