P. chain sword ( E. Tenellus??) is a little more "spear shaped" the sag. Also the sag will not grow as tall as the sword.
Tenellus is also bigger. Will grow to about 2 1/2 to 3 inches. Sag is only about 2.0 inches.
The best way is to take a close look at leaves. cannot describe it easily but the leaves are VERY different.