casting - How to use cast and pointers with malloc and sizeof

I am confused about when to use a cast with malloc in C. What is the difference between these 2 pieces of code (the code in question is the function that initializes a linked list):

1st Excerpt:

  struct QueueNode {
  char content;
  struct QueueNode* prev;
  struct QueueNode* next;
 };

  struct Queue{
  struct QueueNode* first;
 struct QueueNode* last;
};  

Initialisation of the Queue:

Queue* queueCreate() {
Queue* q = (Queue*) malloc(sizeof(Queue));
q->first = NULL;
q->last = NULL;
return q;

}

2nd excerpt:

typedef struct Element Element;
struct Element

 {
 int number;

 Element *next;

 };

typedef struct List List;
struct List
{
 Element *first;
};

Initialisation of the Queue:

List *initialisation()
{
List *l = malloc(sizeof(*l));
Element *element = malloc(sizeof(*element));

if (l == NULL || element == NULL)
{

    exit(EXIT_FAILURE);
}

element->number = 0;
element->next = NULL;
l->first = element;

return l;

 }

This is what I don't understand:
why in the first excerpt do we use a cast (Queue*):

 Queue* q = (Queue*) malloc(sizeof(Queue));

while in the 2nd excerpt, there is no cast but we pass a pointer (*l) to sizeof, and there's no cast?

Liste *l = malloc(sizeof(*l))

So I guess the problem is when to use the cast and when to pass a pointer to the sizeof function.

ps. I read some answers here on so like this one Using malloc() and sizeof() to create a struct on the heap

it's about c++ and it says you have to add a cast. In C, does the cast depend on the type of implementation?

Thank you for your help