I have heard people saying these two phrases, do they have any difference from each other?
For example
I have accomplished a lot across the year.
and
I have accomplished a lot throughout the year.
Is there any difference, or is either wrong?
I have heard people saying these two phrases, do they have any difference from each other?
For example
I have accomplished a lot across the year.
and
I have accomplished a lot throughout the year.
Is there any difference, or is either wrong?
For USA standard English speech and writing, "across the year" is unusual and uncommon, although it is understandable as a phrase referring to a one-year time period (a calendar year or the previous 12 months). These phrases are much more common:
I have accomplished a lot over the course of the year.
I have accomplished a lot during the year.
I have accomplished a lot throughout the year.
I have accomplished a lot this year.
I have accomplished a lot in the last year
The "across" version is quite unusual, and the "throughout" version sounds a bit stilted. The most common way of expressing this (I'm imagining an annual performance review):
I've accomplished a lot this year.
If the context doesn't make clear that this refers to the past twelve months, one could also say
I've accomplished a lot this past year.
My answer holds for US English -- I can't vouch for other flavors.
I checked the link you provided in a comment. The speaker's context is quite different from "I accomplished a lot [preposition] [time period]." In the TED talk, the speaker was talking about the calendar, the months of the year. "Across the year" makes sense in that context. We can see the months ticking by as we go along the timeline. In that context, "across" is probably better than "throughout," because "throughout" suggests that something is constant, or fairly constant, for all 365 days.