Technically a blog is a website, but let’s not get existential here. The difference between a blog and a website comes down to how it’s structured. Both are web addresses on the internet (www.website/blogname.com). The difference comes from the purpose and construction of the page when you land on it.
A blog is a series of “posts” which are essentially articles of varying lengths, organized by date or category. A website is more of a jack-of-all-trades. It will have the main page, a product or services page, a contact page, and so on. Many of these things could also appear on a blog, but the main difference is that a blog is updated far more often than a website which is more of a static design.
Think of a business or a restaurant. Now, think of their website. It’s usually the same, and it very rarely has new or drastically different content. Now, think of a blog you like. It can be about anything, but the difference is that when you visit the blog, you expect a new article or post.