How is the burial and compaction of sediments that create sedimentary rocks different than..

the high temperature and pressure that create metamorphic rock?

The changes that take place is the sedimentary environment do not modify the grains in the resulting rock. The temperatures and pressures are too low. Diagenetic changes are possible.

In the realm of metamorphism the grains begin to change by either aligning themselves perpendicular to the pressures applied and/or going through a recrystallization process which changes the mineralogy of the grains. The bulk composition remains roughly the same (some volatiles are lost), but new minerals are formed. The resulting metamorphic rock could be recrystallized and/or foliated.