I researched the meaning of this expressions in the Longman Dictionary and I found this:
reassure: to make someone feel calmer and less worried or frightened about a problem or situation
soothe: to make someone feel calmer and less anxious, upset, or angry
Both are related to make someone feel calmer. But I don't feel comfortable in them in a sentence.
I've tried to figure out and searched in the Internet the difference between them but I've not succeed.
Please, could someone help me out?