Marco,
* (star) series are meant to be the professional ones while Limited series go for creative work. Feel confused? It's ok, you're not alone - in many languages the word 'professional' is used the wrong way nowadays.
Professional - that's not meant to be about quality at all, that's
only about money. A professional equipment is one that is designed to earn money, nothing more nor less. Yep, it may be considered to be built on some level that is
de facto assumed as a standard for such equipment for nowadays, but that's an extended term interpretation.
You helped somebody and got paid? You're a pro. You did something for free? You're an amateur. Is the professional work always better then amateur? No, it's only the paid one.
If you've got to be the 1st kid on the block, then you need * series (whenever silverish FA* or blackish DA*) since these boys are big and noticeable. You need something special? Go study specs and rendering for each lens. You're tight in the weight and size? Forget the stars, go Limited.
Good luck,
Zig
P.S.
If it makes it any bit clear, let me put it this way:
- a professional drill has the power rating specified for a given duty cycle (e.g. 1.5kW @10/25: for 10 minutes of load and 25 minutes of idling rest afterwards)
- an ordinary drill goes with power rating only
Although this post scriptum may give you more confuse that you're having right now