what exactly is the diff in leather grades with "full top grain" besides price?

i live in california. im considering ordering from a NC site that currently has free shipping. the site says "we only use full top grain leather". but they all still have grades 1-6. so besides price, is grade 1 suppose to show wear and tear before grade 2, 2 before 3, etc.??? i don't know the rules here so i won't post the site. but is it possible they just say its all full grain but grade 1 is actually split grain?

Assuming they follow standard grading practices, the grade is not related to durability, but is related to the cost of the leather -- the higher the grade, the higher the cost. Some very high cost leathers are very beautiful but, because of their nature (e.g., lambskin), their lack of protective treatment, and the like, they may be significantly more vulnerable to wear and damage than a lower grade of leather.

Nothing is ever 'Free' in this business, you're paying for it one way or another - those 18 wheelers don't run on water. :)

When leather comes off the cow its very thick and must be split, its too thick to use otherwise. The upper half of the hide will be "Top Grain", the bottom half is called 'The Splits". Some companies will use "The Splits" on non-stress areas like the sides and backs to save money, however reputable makers do not. Splits have no cellulose strength are not as strong as top grain. 'Full Top Grain' means an aniline dyed hide. The top grain leather has not been processed (to become a finished, painted or protected leather). I seriously doubt if the lower grades are Full Top Grain, normally those are the Finished hides and those are simply Top Grain.

Read A PRIMER IN LEATHER here in the forum under the LEATHER section for more.