Answer

The main difference between the two ranges of water baths, apart from the design, is that the NE2 series has a higher accuracy/sensitivity than the NE1D series.
The NE2 baths have a 0.1 degree C resolution (0.1 degree increments), whereas the NE1D baths only have a 1 degree C resolution i.e. can only be set in 1 degree increments.
The NE1D series was designed with educational use in mind, to offer a more economical version which is more affordable for schools.