Different types of USB cable

I have 30-pin-to-USB cables that came with iPod touch 3rd generation, 4th generation, and iPad 3rd generation. Are the cables different? If so, how can I identify which is which? I notice differences in the width of the cable, color of the plastic part on both sides of the connector (gray vs. white), and the length of the rubber tube that covers the connector, but am not sure if these are just minor variants or they are different products.

I know that the newer models accept 2A current, as opposed to 1A on older models, and the AC adaptors are designed differently accordingly, but was not sure whether the cables are also different.

Solution 1:

The older USB cables from iPod days have deeper and thicker plastic enclosures on the 30 pin end as well as physical buttons on the sides to help disengage the metal "ratchets".

The connectors that came with the iPhones had much weaker springs for the side "ratchets" so you could just pull to detach the connector.

Here is a Bluetooth iPhone charger (that is slightly larger and thicker than the iPod model) with a current iPhone cable for comparison.

The cables are all functionally equivalent once seated so you don't need to worry about current or power since even the oldest USB cable can carry all the signals needed for the latest iOS products and chargers.