What's the difference between glMatrixMode(GL_PROJECTION); and glMatrixMode(GL_MODELVIEW);

Code :
#include <stdio.h>
#include <GL/gl.h>
#include <GL/glut.h>
 
#define KEY_ESCAPE 27
 
void display();
void keyboard(unsigned char,int,int);
 
int main(int argc, char **argv) {
    glutInit(&argc, argv);                                    
    glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE|GLUT_DEPTH );
    glutInitWindowSize(600,400);                  
    glutCreateWindow("Opengl Test");                              
    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);
    glutMainLoop();
    return 0;
}
void display() {
    float x,y,z;
    int i;
    x=0;
    y=-0.8;
    z=0;
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1,1,0);
    glBegin(GL_POINTS);
    for(i=0;i<98;i++) {
        glVertex3f(x,y,z);
        x=x+0.01;
    }
    glEnd();
    glutSwapBuffers();    
}
void keyboard(unsigned char key, int mousePositionX, int mousePositionY) { 
    switch ( key ) {
        case KEY_ESCAPE:
            exit ( 0 );   
            break;      
        default:      
            break;
    }
}

Code :
#include <stdio.h>
#include <GL/gl.h>
#include <GL/glut.h>
 
#define KEY_ESCAPE 27
 
void display();
void keyboard(unsigned char,int,int);
 
int main(int argc, char **argv) {
    glutInit(&argc, argv);                                    
    glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE|GLUT_DEPTH );
    glutInitWindowSize(600,400);                  
    glutCreateWindow("Opengl Test");                              
    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);
    glutMainLoop();
    return 0;
}
void display() {
    float x,y,z;
    int i;
    x=0;
    y=-0.8;
    z=0;
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1,1,0);
    glBegin(GL_POINTS);
    for(i=0;i<98;i++) {
        glVertex3f(x,y,z);
        x=x+0.01;
    }
    glEnd();
    glutSwapBuffers();    
}
void keyboard(unsigned char key, int mousePositionX, int mousePositionY) { 
    switch ( key ) {
        case KEY_ESCAPE:
            exit ( 0 );   
            break;      
        default:      
            break;
    }
}

For both codes, i get same result.
Can anyone show the difference of these glMatrixMode(GL_MODELVIEW); and glMatrixMode(GL_PROJECTION); changing this code?