If I understood you correctly:
<?php
//if home, do nothing
if( ! is_home() || ! front_page() ) {
//if has post thumbnail
if( has_post_thumbnail() ) {
the_post_thumbnail( 'full' );
echo '<h1 class="entry-title">'. get_the_title() .'</h1>';
} else {
//no post thumbnail, show normal entry title
echo '<h1 class="entry-title">'. get_the_title() .'</h1>';
}
}
or, it can be done easily:
<?php
if( ! is_home() || ! is_front_page() ) {
if( has_post_thumbnail() )
the_post_thumbnail( 'full' );
echo '<h1 class="entry-title">'. get_the_title() .'</h1>';
}