Answer:
Letter of interest: Expresses your interest in working for a company.
Cover letter: Discusses how you meet the job requirements
Thank you letter: Reiterates why you are the best candidate for the job.
Letter of recommendation: Tells more about your character and who you are.
Step-by-step explanation:
A letter of interest is a document you sent to a company to let them knoe that you are interested in working for them and find out about available opportunities.
A cover letter is a document you sent with your resume in which you introduce yourself and explain how you are a good match for the position.
A thank you letter is sent after an interview to thank for the opportunity and to reinforce that you are a good candidate for the job.
A letter of recommendation is a document in which the author talks about the character, qualities and skills of another person that they are recommending.