Compare and contrast some of the characters who serve as foils throughout Jane Eyre: Blanche to Jane.

Jane Eyre and Blanche Ingram share several similarities. Blanche does not have much money, as most of it must go to her brother: we learn from Mrs. Fairfax that "neither she nor her sister have very large fortunes." Jane too lacks money. She is poorer than Blanche, as she has no money at all. Both women are much younger than Rochester. Both women also have a romantic interest in Mr. Rochester, although Blanche is more interested in Mr. Rochester's money and status than Jane is.
The two women, however, are primarily different. Jane is small and plain, the kind of person who could be easily overlooked, while Blanche is tall, beautiful, and dominating. She is described by Mrs. Fairfax as

Tall, fine bust, sloping shoulders; long, graceful neck: olive complexion, dark and clear; noble features; eyes rather like Mr. Rochester’s: large and black, and as brilliant as her jewels.

Unlike Jane, Blanche can sing and play the piano. Also unlike Jane, who is quiet and likened to a simple Quakeress, Blanche is proud. We learn that

her laugh was satirical, and so was the habitual expression of her arched and haughty lip.

Blanche describes her "merry days" in childhood tormenting her governess. Jane, who is a governess, is not amused by her stories. Blanche is described as "haughty" and "queenly," very different from Jane. Jane, a product of the Lowood School, has been taught to be humble and unassuming.
That Mr. Rochester falls in love with Jane rather than Blanche is a testimony to the strength and goodness of Jane's character. That Blanche is a competitor shows as well that Mr. Rochester freely chooses Jane: he could have had a woman that most of the world would have thought a much finer mate, and yet he follows his heart in preferring Jane.
If you would like comparisons and contrasts of other foils to Jane, you could submit another question. St. John is another foil in his emotional coldness compared to Jane's warmth of feeling. The Reed children are also foils in being petted and spoiled while Jane is abused.