TB vs. NTB CPU & Ram Differences

Hello!

I just received my new TB 13" with 2.9GHz i5, 16 gigs of ram and 256 SSD. I ordered it on the unveil day, but have been pretty disappointed by early reviews saying the battery isn't lasting as long as the NTB in testing.

At BHPhotoVideo I found a NTB with 2.4GHz i7, 16 gigs of ram, and 512 SSD for $1,999 shipped ($200 discount). That's actually cheaper than my current setup!

What I'm wondering are two things.

1) What is the difference in styles of ram between these two systems? Is the 1866mz noticeably slower than the 2133mz?

2) What will the speed difference be between the upgraded 2.4GHz i7 of the NTB and the 2.9GHz i5 of the TB be? Why is the slower rated processor an i7, while the faster one is a 2.9GHz?

I'm trying to figure out if these two devices will give similar real world results? If the trade off is a longer batter life and double the SSD space at the expense of the touch bar, I think I'll take the plunge.

Thanks in advance!