Dithering is the method by which an audio clip's bit depth is changed (the most common dithering is from 24bit to 16bit, which is cd-audio word length). Additionally, many A>D converters convert the signal at a higher bit depth and dither on output. For example, the Grace Designs Lunatec V3 converts at 24bit and dithers on output using the ANSR dithering algorithm to create a 16bit audio clip, if the ANSR circuit is engaged.
Resampling is the method by which an audio clip's sampling rate is changed, for example from 48khz to 44.1khz (44.1khz is the sampling rate for cd audio).
Specifics will obviously vary depending on [a] the bit-depth (24 or 16), sample rate (96 or 48), [c] software in use, but always remember (thanks to the many that have posted this already elsewhere):
 Perform all editing first
 Convert bit-depth to desired word length