The main difference between evenweave linen and regular linen, is that the stitches per inch may not be the same count vertically and horizontally. Linen is a natural fibre fabric. Therefore linen threads do not all have the same thickness. Evenweave linens is woven in such a way that they have equal amount of stitches per inch. Other linens may not have the same count.
Both a regular linen and an evenweave linen can be used perfectly for free hand embroidery projects. For cross stitch projects an evenweave linen is recommended.