No, it's completely different. Sodium Bicarbonate, helps with very lactate concentrations in very short events e.g., < few minutes, at buffering lactate. In (i think) ~50% of people who use bicarb loading (you need very high doses for it to work), there are bad gastro intestinal side effects :-(
Sodium Phosphate, is thought to work in two different ways, which as yet have yet to be fully elucidated. These include increased heart alterations, or changes to blood biochemistry. Phosphate does not lower lactate concentrations. It appears that with phosphate loading, fitness is temporarily increased with an increase in VO2 max, LT, and performance (see, Kreider et al, Stewart et al, Stern et al), however, some there are equally many studies (although these mainly used calcium phosphate) that show no effect on performance or physiological variables (e.g., Mannix et al, Kraemer et al and i think Galloway et al).
In the studies that show an ergogenic effect, the effect lasts ~10-days. Depending on the method of consumption, and with sensitive people, sodium phosphate can have some very nasty, almost instantaneous side effects :-(