What Mary-Lorraine says, lo que ella dice es correcto. Ambos son correctos, pero hay un poco de diferencia. "She started work" significa 'ella empezo el trabajo' o ella empezo un puesto. Work aqui es un nombre/sustantivo. "She started TO work" significa 'ella empezo trabajar'. Entiendo ahorita: To work, es el infinitivo, y es un verbo, el acto de trabajar. Si hay un series de verbos, solo el primer se modifica (conjugar?) y los siguientes no se conjuguen.

she started work "to" is not included, because we do not mean she started to work on a specific task, but that she started work (a new job) she started to work Yes, this is also correct, but means she started to work on a specific task. Please forgive me for not responding in Spanish. I can understand it, but do not write it well.

Both are correct. The difference is that in the first one 'work' is a noun, and in the second, it is a verb. The first one is similar to 'She started her job'. Or, an expanded version: 'She started the work that she should have finished last week'.