Spacer vs coilover adjustable strut lift. Front end geometry difference?

So, I have read a lot of threads and comments saying to avoid (above strut mounted) strut spacers because they change the suspension geometry which puts the steering and suspension components under too much stress.
With this type of lift the ratio of lift compared to the thickness of the spacer is 2 to1.
meaning, if the spacer measures 1" thick it will produce 2" of lift.

While the spacer style lift is frowned upon because of potential damage, the coilover adjustable strut (IE; Bilstein 5100 w/ Eibach extended springs) lift is highly recommended and very commonly used.

I understand the benefits and drawbacks of both types of lifts as it pertains to offroad capability.
That's not my question.

The way I understand it (if I'm wrong someone please correct me), The "Bilstein / Eibach strut assembly is longer than the stock strut assembly. so when it is installed the increased length of the strut assembly is what provides lift.
Where as the spacer simply increases the length of the stock strut assembly which provides the lift.

My question is, How is one potentially less damaging than the other?

They both work off of the same principal, Increase length of strut assembly to produce lift.

How does one change the front end "geometry" too drastically and the other doesn't.

Again, I'm not asking about the benefits of one compared to another as far a ride quality, or off road capability.
I simply want to know how the geometry changes are different for the two lift styles that use essentially the same method to provide lift.

 

^^^ what he said. Strut spacers especially the 3" lift ones will over extend ball joints when when the tire drops

 

Would like to revive this thread as the question was posed very well and did not get much response. I just purchased front B 5100 and was planning to lift 1-1 1/2' until I measured and found that even 2 1/2" won't get my truck level. Was planning to use stock springs, but now seeing I need more, I am concerned about geometry and spring rate with this set up. Any insight and suggestions welcome.