Dunno if you still need a response to this, but...the difference is actually quite large:
Stats 2B03 is introductory level statistics, whereas stats 2D03 is designed for math&stats majors who have encountered statistics before. It involves more complex ideas, computations and even a slight bit of proofs.
2B03:
Major Topics: Describing data, graphical representations of data, probability, confidence intervals, hypothesis testing, one-way ANOVA, analysis of categorical data, regression and correlation
2D03:
Major Topics: Combinatorics, independence, conditioning; Poisson-process; discrete and continuous distributions with statistical applications; expectation, transformations moment-generating functions; introduction to statistical inference.
You can pretty much tell, just by how it sounds, that 2D03 is more intimidating. Also the course restrictions kind of speak for themselves. 2B03 is not open to students with credit in 2D03, but 2D03 can be taken after 2B...because there is still much to be learned.
To answer your other question, yes...Data Management is pretty much Stats 2B03, except for a few topics (like perhaps ANOVA (Analysis of Variance)).