Complex sentence: Heterotopotaxy is a process similar to heteroepitaxy except that thin film growth is not limited to two-dimensional growth; the substrate is similar only in structure to the thin-film material.
Split into simpler sentences: Heterotopotaxy is a process similar to heteroepitaxy except for the fact that thin film growth is not limited to two dimensional growth. Here the substrate is similar only in structure to the thin film material.