Momentous
Part of speech: adjective
Definition: outstanding in importance unparalleled significance
Example sentence: I always have a lot of things going on because some things take years to make and others take five minutes. I like that there's always something going on. Working doesn't have such a momentous feel - like it's all or nothing.
Important
Part of speech: adjective
Definition: Having relevant and crucial value.
Example sentence: It is nice to be important, but it's more important to be nice.