There is a continuum of access, from most restrictive to most open. The following are the key terms you need to know.
For information about open licenses, please see the Open Licenses/Creative Commons Licenses section of this guide.

Paywall journals (a.k.a., toll journals) follow the traditional publishing model: readers have access only by purchasing a subscription or an individual article. Authors may or may not pay a fee to publish articles. Paywall journals are the most restrictive.

Hybrid journals offer a combination of open access (i.e., the content is free to read immediately upon publication) articles and articles behind a paywall. Authors who choose the open access option assign the article an open license and pay a publishing fee called the article processing charge (APC).

Gold journals (a.k.a., open access journals) make their entire content open. Authors assign the article an open license and, often, pay an article processing charge (APC). Gold journals are the most open.

Green articles are published in paywall journals, but they may be posted in an open access archive or repository where they are freely available. These repositories may be discipline-specific (like ArXiv) or institutional repositories operated by universities or other institutions. Green articles in a repository may be published versions or preprints, and authors may or may not assign them an open license.

Bronze articles are free to read on the publisher's website; they do not have an open license. There may be a delay between publication and availability as open access, and often the publisher can remove articles at will.  

Closed articles are behind a paywall where readers can access them only by purchasing a subscription or an individual article.