逃げが得意なウマ娘
先行が得意なウマ娘
差しが得意なウマ娘
追込が得意なウマ娘

みんなちがってみんないい

There are Umamusume who are good Runners.
There are Umamusume who are good Leaders.
There are Umamusume who are good Betweeners.
There are Umamusume who are good Chasers.

They are different, but they are all great.

Refer to 'pacing' strategies, which are real-life horse-racing tactics that also function as in-game 'soft'-classes (tactic preference) in Umamusume. Leaders lead the front of the 'pack', Runners try to break ahead of the pack, Betweeners try to maintain position within the pack, and Chasers generally hang back but will pick up the pace near the end when the pack disperses.

These are not hard delineations; horses (and their jockeys) will often blur the lines between one or two pacing strategies and may switch things up from time to time. But generally a horse (and the corresponding horsegirl) will tend to favor one or two pacing styles, depending on 'genetics' and how they are trained.