I was in AP World last year and got a 5, but the test might be changing this year, so I’m not sure how much I can help you. However, a thesis is still a thesis, and while yours shows a good mastery of language and style, it is vague. Also, remember that your thesis can be more than one sentence, but you should go with what style fits best for you.
You don’t want to give too many details in the thesis (save your evidence for the body paragraphs), but you need to provide some more elaboration on exactly what their objectives were and what aspects of their religions made them different. It’s hard to explain, but you need to be specific enough so that the reader knows exactly what the focus of your essay will be, but general enough so that major details are left for your supporting paragraphs. Format is not really your issue here, because your structure is fine. Your problem is making the thesis too general so that the reader won’t know what your essay will exactly be about. Consider the following examples that I’ll make up:
“Imperial Spain and Britain had similarities in their economic goals, but there were differences in how their colonies developed.”
“Imperial Spain and Britain were similar in that they had goals to extract wealth from colonized lands in the New World. However, Spain’s colonies developed from a system of subjugation of the native population and massive exploitation of resources while Britain’s grew by creating colonial communities composed of opportunistic English immigrants.”
“Similarities existed in how both Imperial Spain and Britain sought gold and other rare resources in the New World to gain wealth for their respective monarchs; doing so allowed both of them to become prominent European powers with influence over the rest of the world. Britain, however, developed societies of mostly English immigrants who sought a better life in the colonies, such as the Puritans who were looking for religious freedom. On the other hand, Spain had relatively limited immigration and instead focused on creating labor systems called encomiendas that allowed the Spanish monarch to achieve unprecedented wealth and over-abundance of silver.”
Examine the first thesis’s claims - “similar economic goals” & “differences in how they developed”. That is very vague because it doesn’t specify or analyze their economic goals. “Economic goals” could mean a lot of different things, and your reader isn’t going to infer it from your thesis. The same thing applies to “how their colonies developed”. You have to give more specific detail on exactly how they developed.
The second thesis is your ideal one. It clearly specifies the types of motives that both Spain and Britain had - they wanted to extract wealth from the areas they colonized. Then, it focuses on exactly how their development differed - Spain’s was based on subjugation and exploitation of resources while Britain’s was based on distinct English communities. It saves all key details for the body paragraphs, like encomiendas, Spanish silver, Puritans, Jamestown, etc, but includes what major points the rest of your essay will discuss.
The third thesis is obviously too much. There are way too many details that should be put in the body paragraphs, and it isn’t effective at being concise and to the point.
What you’re doing is only listing the categories or aspects that they had similarities and differences in; you need to concisely specify what those aspects include for the things you’re comparing. Again, you can go with whatever format that works for you, but remember to explain the major points of your essay without making it too general or using important details for the body paragraphs. Revise your current thesis and post it as a reply to me.