Sparkly –
By memorization I mean exactly what it sounds like. I will give you an example. Conceptually, you need to understand oxidation of alcohols. You need to know the difference between primary, secondary and tertiary alcohols and understand how oxidation of alcohols works. Which ones get oxidized to ketones, which to aldehydes, which to carboxylic acids. Understanding that is conceptual. The memorization aspect comes into play when you are asked HOW to actually do that. Which oxidizing agent should you use if you want to generate butanoic acid from 1-butanol? Which would you use if you wanted butaldehyde instead? What if you wanted to oxidize 2-butanol to butanone? This involves you understanding the concept of oxidation, of course, but also requires that you have memorized a list of oxidizing agents and memorized which is appropriate to use in which situations.