Yes, they are different. Directory submissions essentially involve having your website details submitted along with titles and descriptions about your product or service to online directories. The purpose of making directory submissions is to get links with relevant anchor/link texts (titles), placed under relevant categories.

Article submissions on the other hand, involve writing articles related to the theme of your website and having the same submitted to article directories. The purpose of article directories is to share relevant content that may be reproduced by other website owners on their websites, free of cost. In return for this, the author would get a link with each article reproduced, which will include his name and the company or organization he represents.