People pay attention to A and B but honestly speaking, it makes no difference. Sometimes A can be worse than B.
And your broker A book can be someone else B.
Very few people know whether or not they are on an A Book or B Book and most don't even know what we are talking about here actually. Theere are FIVE A Book brokers in the world, and only ONE broker I know of does NOT have a B Book. All the others have a B Book. So, depending on what the broker decides or agrees upon with the trader, they will be put on one or the other. Even though people THINK they might be on an A Book, most are NOT.
It makes a huge difference for the trader because when on B Book the broker is normally taking the opposite side of the trade. When you win, they lose. When you lose, they win. If the broker is big, they can usually handle withdrawals. But, if you put in 1M and made 10M in profit and tried to pull it out, MOST brokers would give you push back on that because that is a 10M loss to THEM. So, sometimes it can be hard to get your money. THAT is a big difference. When on a PURE A BOOK broker (only one I know of) there will never be an issue getting a withdrawal because the trades went directly to the market and a POOL of liquidity providers means virtually unlimited liquidity.
The downside of an A Book broker, if we can call it that, is that it is REAL. So, you will have to adjust your trading to a REAL market environment where the broker is not in the game AT ALL.
To determine if your trades are REALLY on A Book, just ask for a time of sale stamp. If they cannot provide it, you are certainly on a B book.
The Leader Board on the A Book I use are knocking it out of the park.
This broker is built BY traders FOR traders and that makes the big difference.