You may have noticed there are some parts, like Peak-System’s IPEK-003009 and IPEK-003019 that seem to have little to no difference beyond the price. This is because the 3019 variant is SAE J1939 Type 2 compliant whereas the 3009 is Type 1 compliant.
So what does this mean, exactly? The SAE J1939 communication standard, like many others, gets upgraded over time as the technology it uses gets more advanced. Where some standards go obsolete to make way for their successors, the SAE J1939 Type 2 was designed with backwards compatibility for Type 1. This allows for integration of SAE J1939 to operate with Type 1 while slowly moving to Type 2.
It is important to note, however, that these communication types are only as fast as the slowest device. This means if you have a full system of Type 1, then having a Type 2 cable is not going to increase your performance. This is why some companies like Peak-System make both the Type 1 and Type 2 cable. In cases such as this, the decision point typically comes down to current cost vs. upgrade cost.