Answer:
Appendices are attachments to an essay. Two materials that you can include in the appendix of a long essay are;
Images and Charts.
An abstract is a summary of the aim of a research paper. It helps readers to quickly have an overview of the essay, its intent, and key findings.
Appendices are attachments that are found enclosed with the main essay.
Materials that are added to appendices are those that could make the essay cluttered but could provide additional knowledge on the subject being discussed.
An abstract on the other hand is found at the inception of the essay and provides an overview of the material being discussed.
