A distinction is when you're in the top 10 placing for the whole week of entering either the english or western grand prix.

Link for info in Game Help

Completely impossible for the majority of players and even to try means you need to spend 1000s of passes and know how to properly train 5 horses to top skills in one week.

Personally I just ignore it even though I have a credit for it due to an error way back

The game is far more likely to close before I'll ever get it. I have rarely missed a day let alone an entire week and it takes at least one shiny "new" pixel among the five each week to be able to get into the top 10 and that's only "if" the other ones are less than three weeks old.
It likely costs 1500 passes on average and that's when one of the bonuses are in stock like wings, a dial, woy or the newish stone. For some breeds, they can finish top 10 for two weeks and sometimes three but for the most part, they're really only useful for three weeks. Plus, you need the tack packs to be at the top and you need to be at the top or close to it at least once to finish top 10 for the week. For those who can skill five per week, every week, they deserve that trophy

Now if it were the top20 I would've had it ages ago as I'm rarely out of that range, but as of now, I'm at 71.