At present, L2B has two series, ptrc and stec, but they are still different, because the R&D team and origin are different. L2B is an old GM machine used directly. Ptec can be understood as upgrading from old L2B, and stec can be understood as upgrading from ptec.
Therefore, L2B is mostly used for old models, ptec is mostly used for domestic cars, and stec is used for general joint venture cars. After all, the original car price is different, and the engine can't be exactly the same.