先看一下英文的解释：
tend sb 照看
If you tend someone or something,you do what is necessary to keep them in a good condition or to improve their condition
“照看”某人或某事,就是说,你必须尽力保证他/它处于一个状态良好或改善他/它的现状
tend to sb 关照
If you tend to someone or something,you pay attention to them and deal with their problems and needs.
“关照”某人或某事,就是说,你对他/它面临的困难和需要表示关注.
前者是责任（责无旁贷）,后者是义务（伸出援手）.