这两个结构定义之间有什么区别？

What is the difference between these two struct type definitions?

var query1 struct {
    A, B string
}

query2 := struct {
    va1 string
    va2 int
}{"Hello", 5}

Why can I not initialize the first with value like second? What is the difference between them?

You can "initialize the first with value like second." For example,

package main

import "fmt"

func main() {
    var query1 = struct {
        A, B string
    }{"Hello", "5"}

    query2 := struct {
        va1 string
        va2 int
    }{"Hello", 5}

    fmt.Println(query1, query2)
}

Output:

{Hello 5} {Hello 5}

query1 is a variable declaration. query2 is a short variable declaration.