I have derived elevation profile of a river channel using USGS SRTM 1 ArcSec. I am interested to know whether Elevation Profile and Longitudinal Profile are synonymous?
An elevation profile or a topographic profile is a two-dimensional cross sectional view of the landscape. It provides a side view of the relief of the terrain along a line drawn between two locations on a topographic map.
Whereas, the longitudinal profile is a two-dimensional view along the river, and it characterizes average stream slopes and depths of riffles, pools, runs, glides, rapids and step/pools. Longitudinal profiles are measured in the downstream direction.
In your case you said you have derived elevation profile of a river channel, which I think it is longitudinal profile.