i found a good supplier for solvents here where i live very cheap to and they had 2 types of naphta one that is pure naphta and the otrher one is naphta 4 what is the difference of these naphtas i i am thinking that pure naphta is better just logic but i was wondering what is naphta 4

I can't answer your specific question, naptha isn't a specific chemical as such, each company makes its own blend, refer to:
Wikipedia Naptha Article

Generally, the 2 main types are heavy naptha and solvent naptha, one being used for fuel and the other for solvent purposes. Solvent naptha is better than heavy naptha for extraction purposes but that doesn't at all mean heavy naptha doesn't work.

The difference is likely to be that one is heavier than the other, and as a wild and probably wrong guess, the 4 in naptha 4 could refer to the average length of the carbon chain?