Well, there is a lot of overlapping nomenclature. Here by variant we understand any sample, which is not identical sequence-wise to sequences seen before. Most of the observed mutations are innocuous and do not lead to a potential new lineage (what better fits the definition of variant above). However, it is difficult to tell by eye - or even with the standard computational tools - if new mutation is (a) deleterious (harms the virus' capacity to spread), (b) neutral, or (c) fitness enhancing.