Salesforce Marketing Cloud - Free Form, HTML Content, and Code Snippets
As part of our Content Builder FAQ series, we are today explaining differences between three types of content blocks, which are difficult for many users to distinguish from one another: Free form, HTML content and Code snippets. What all three blocks have in common is that they first look “empty” when you insert them into an email or template. But how do they differ and when should you use which block?

The Free Form Block Is the only one of these three blocks that has a WYSIWYG editor and therefore has a direct preview. With this block, template or email elements can be created that differ from the standard layout blocks. While tailor-made adjustments take place in the HTML of the block, some editing steps can also be carried out later by the end user in the WYSIWYG editor. The block is therefore particularly suitable for creating custom design blocks when creating templates, which are then also used by People with little HTML knowledge can be used.
The HTML block is intended to copy ready-made HTML and CSS-based content directly into the email. It is different from the Free Form block in that it no WYSIWYG editor provides. Adjustments to the block are therefore only with HTML knowledge possible. The inserted HTML is placed in a table that has the same styling as the template used. The block is therefore a good way for HTML-savvy users to integrate complex content directly into the existing email or template framework via HTML.
that Code snippet On the other hand, it is primarily used to AMPscript or GTL to place in an email. In contrast to the HTML block, a table is not automatically created around the block — which means that comprehensive template stylings do not apply here unless you insert them yourself. This is ideal for integrating email scripts, but also for calling up blocks of content that have already been saved elsewhere.
The three blocks are therefore only similar at first glance — when viewed more closely, they have clearly defined functions and are used for various purposes.
Here you can find detailed information.