form1.designer.cs is an auto-generated file that corresponds to form1.cs. The idea is that the Visual Studio form designer can put its auto-generated code in form1.designer.cs without having to worry about messing up any changes that you may have made.
form1.resx is most commonly used for storing strings that you want to translate into different languages so you don't hardcode them into your app.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…