which difference between Sayc and Acol ?

[joshs]

BTW, the one time I played ACOL in a real event, it was a very americanized version:

 

1. Weak NTs

2. 4 card majors but we usually opened a minor with 4-4 unless the major was much better

3. 2/1's promising a rebid

4. Bergen raises (I actually like these much better playing 4 card majors and a weak NT than playing 5 card majors)

5. Constructive single raises, which usually have only 3 card support

6. 1X-1N-2N was 17-18ish

7. A mini-multi 2D with Intermediate 2's

8. Non-forcing single raises in the minors, and criss-cross as the forcing raise

[EricK]

Here is something interesting (if slightly off-topic):

 

In traditional Acol a 2/1 showed about 8+ points. In traditional SA a 2/1 shows about 10/11+ points. In both cases the 2/1 bid shows enough strength to have a shot at 2NT should partner turn up with a minimum balanced hand (15 points in Acol, 12 in SA).

 

In more modern versions of Acol the 2/1 shows about 10+ points, whereas in more modern American systems the 2/1 shows 12/13+ points. i.e in both cases the 2/1 has become just strong enough to have a shot at 3NT should opener have a minimum balanced hand.

 

The ability for opener to simply rebid a forcing 2NT after a 2/1 and not have to jump to 3NT with a little extra is, IMO, the biggest reason for the shift in both cases.