WordPress is a very powerful and flexible platform because you can modify the codes to do almost anything you want to. So WordPress is highly customizable.
However, this is only applicable to you, if you are very good with coding or if you’ve hired a skilled developer to help you.
A capable and reliable coder from a developed country could cost you about US$100 per hour. It could be a bit cheaper if you hired someone from a developing country. So the cost can quickly add up.
If you prefer not to pay for help, you better be pretty proficient with codes (or learn to become proficient) if you want to make design changes to your website.
Even though WordPress is much more flexible than Squarespace, its learning curve is a lot steeper than Squarespace.
With Squarespace, it is a bit more restrictive when it comes to customizing a website, but it’s built in a way that it is a lot easier for a non-tech savvy person to learn how to use it.
Squarespace is a WYSIWYG (What You See Is What You Get) website builder. Meaning that when you drag and drop pictures, text, slideshows, etc directly into the website builder, you immediately get a glimpse of how the website will look like “live” as you are building the website.
With WordPress, when you are inserting information, you can’t see what it really looks like on the page until you preview the page or publish it.