Weird behavior when casting void*

Question

I'm trying to create threads in c and I had to pass an argument to threadRunFunction but I stumbled upon some warnings.

First prototype (Doesn't contain warnings when compiling it and when using long int):

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

#define CHECK(func, msg) if ((func)) fprintf(stderr, "ERROR: %s\n", msg);

#define N_THREADS 10
pthread_t thread[N_THREADS];

void* threadRunFunction(void *param) {

    const long int thread_number = (long int) param;
    printf("Thread #%ld running...\n", thread_number);
    return NULL;
}

int main() {
    for (long int i = 0; i < N_THREADS; i++) {
        CHECK(pthread_create(&thread[i], NULL, threadRunFunction, (void*)i), "pthread_create");
    }

    for (int i = 0; i < N_THREADS; i++)
        CHECK(pthread_join(thread[i], NULL), "pthread_join");
    return EXIT_SUCCESS;
}

Second protype (Contain warnings when compiling it and when using int instead of long int):

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

#define CHECK(func, msg) if ((func)) fprintf(stderr, "ERROR: %s\n", msg);

#define N_THREADS 10
pthread_t thread[N_THREADS];

void* threadRunFunction(void *param) {

    const int thread_number = (int) param;
    printf("Thread #%d running...\n", thread_number);
    return NULL;
}

int main() {
    for (int i = 0; i < N_THREADS; i++) {
        CHECK(pthread_create(&thread[i], NULL, threadRunFunction, (void*)i), "pthread_create");
    }

    for (int i = 0; i < N_THREADS; i++)
        CHECK(pthread_join(thread[i], NULL), "pthread_join");
    return EXIT_SUCCESS;
}

These are the warning messages of the second prototype:

main2.c: In function ‘threadRunFunction’:
main2.c:12:29: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
   12 |         int thread_number = (int) param;
      |                             ^
main2.c: In function ‘main’:
main2.c:19:75: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   19 |                 CHECK(pthread_create(&thread[i], NULL, threadRunFunction, (void*)i), "pthread_create");
                     
                                                      

They both run correctly but I want to know the reason why the second one is throwing these warnings and the first one is not.