The word "waiver" in NIW has the totally different mean from the word in J1 waiver.
The former is a category of I-140 process, which doesn't required your J1 waiver. Anyone can apply NIW no matter his current legal visa status is.
The latter is specifically for J1 in order to get rid of 2-year home country residency requirement. There are several ways to get a J1 waiver. The most common and easiest way is to get a "no objection" from Chinese Embassy (represents government), which requires you to be in J1 status for at least 1 year. Of course you have to keep that J1 status until final approval from INS. The other ways doesn't have this 1 year requirement, but they are much harder to get.
The point is without J1 waiver, you can not change your visa status from J1 to others, such as H1b. Also, without J1 waiver, your I-485 will not be approved even you get NIW I-140 approval.
The former is a category of I-140 process, which doesn't required your J1 waiver. Anyone can apply NIW no matter his current legal visa status is.
The latter is specifically for J1 in order to get rid of 2-year home country residency requirement. There are several ways to get a J1 waiver. The most common and easiest way is to get a "no objection" from Chinese Embassy (represents government), which requires you to be in J1 status for at least 1 year. Of course you have to keep that J1 status until final approval from INS. The other ways doesn't have this 1 year requirement, but they are much harder to get.
The point is without J1 waiver, you can not change your visa status from J1 to others, such as H1b. Also, without J1 waiver, your I-485 will not be approved even you get NIW I-140 approval.