go 的struct 跟map赋值不同

package awesomeProject

type Jiegou struct {
   Name string
}
func main() {
   var m map[string]string
   a:=m{"name":"test"}   // map no OK
   //m["test"]="test"    // OK
   b:=Jiegou{Name: "teeee"} //ok
   //b.Name="xxxx"   //OK 
}