display:block跟display:inline-block写不写怎么没区别 啊

    #tabs{width:290px;height:150px;padding:5px;margin:20px;}

    #tabs ul{list-style:none;display:block;height:30px;line-height:30px;border-bottom:2px saddlebrown solid;}

    #tabs ul li{background:#fff;cursor:pointer;float:left;height:28px;line-height:28px;border:1px solid #aaa;border-bottom:none;list-style:none;margin:0px 3px;display:inline-block;width:60px;text-align:center;}