Get images only from a certain post type

You need to put wp_reset_postdata() after each while loop. It is best practice to put after each loop. Once you put, you will get images data for each custom post type.

<?php

    // The Query
    $query1 = new WP_Query( $args );

    if ( $query1->have_posts() ) {
        // The Loop
        while ( $query1->have_posts() ) {
            $query1->the_post();
            echo '<li>' . get_the_title() . '</li>';

            //print post thumbnail
            echo get_the_post_thumbnail(get_the_ID(), 'thumbnail' ); 


            //get post thumb url
            $featured_img_url = get_the_post_thumbnail_url(get_the_ID(),'full'); 

        }

        /* Restore original Post Data 
         * NB: Because we are using new WP_Query we aren't stomping on the 
         * original $wp_query and it does not need to be reset with 
         * wp_reset_query(). We just need to set the post data back up with
         * wp_reset_postdata().
         */
        wp_reset_postdata();
    }

    /* The 2nd Query (without global var) */
    $query2 = new WP_Query( $args2 );

    if ( $query2->have_posts() ) {
        // The 2nd Loop
        while ( $query2->have_posts() ) {
            $query2->the_post();

            //print post thumbnail
            echo get_the_post_thumbnail( $query2->post->ID, 'thumbnail' ); 


            //get post thumb url
            $featured_img_url = get_the_post_thumbnail_url($query2->post->ID,'full'); 
            echo '<li>' . get_the_title( $query2->post->ID ) . '</li>';
        }

        // Restore original Post Data
        wp_reset_postdata();
    }

    ?>