Agree
gusts make it bumpy, you go in and out of eddies, updrafts, downdrafts... IAS will fluctuate. The airplane's energy state remains approximately the same.
WS make it scary, you pass from a headwind to a tailwind, (or the opposite, less scary but tricky) and in the new air mass you will stay. IAS will change, and only will recover with time, depending on the mass of the airplane and the airspeed change. In extreme cases, time is so long that the airplane will crash before it can regain climb performance. airplane's energy state changes (decreasing in the worst case, increasing in the tricky case).
The WS case has to do with inertia. airplanes "inertial speed" (if I am allowed to invent terms) is GS. If the wind speed changes suddenly from a 20 kt headwind to a 20 kt tailwind, GS will still be the same, initially, due to airplane's inertia, and then gradually be increased as the new tailwind airmass "carries" the airplane within it, accelerating it. therefore IAS will instantly be reduced in 40 kt and it should tend to gradually increase until reaching the old value. However this can be difficult since performance will be drastically degraded, L/D ratio will be reduced putting you inside the reverse command region, may be making you fly at the verge of stall and then you are facing a difficult decision: stall recovery (at the expense of precious height) or rate or minimising height loss (at the expense of reduced L/D ratio) while we wait till the WS is over and we cross our fingers