标题里已经把这个意思表达清楚了，两个参数意思一样，只是某大仙觉得match_parent更贴切，于是从2.2开始你两个词都可以用。那么如果考虑低版本的使用情况你就需要用fill_parent了。
下面是两者相同的证据，看android.view.ViewGroup里的静态嵌套类LayoutParams中的代码：
public static final int FILL_PARENT = -1;
/**
* Special value for the height or width requested by a View.
* MATCH_PARENT means that the view wants to be as big as its parent,
* minus the parent's padding, if any. Introduced in API Level 9.
*/
public static final int MATCH_PARENT = -1;
/**
* Special value for the height or width requested by a View.
* WRAP_CONTENT means that the view wants to be just large enough to fit
* its own internal content, taking its own padding into account.
*/
match_parent到底是什么类型呢?
其实从Android 2.2开始FILL_PARENT改名为MATCH_PARENT ，从API Level为8开始我们可以直接用MATCH_PARENT来代替FILL_PARENT，最后提醒大家，他们的定义本质是一样均为 -1，只是换了个别名，可能为了更准确些，
比如最终在SDK中的定义为:
fill_parent -1 The view should be as big as its parent (minus padding). This constant is deprecated starting from API Level 8 and is replaced by match_parent.
match_parent -1 The view should be as big as its parent (minus padding). Introduced in API Level 8.
wrap_content -2 The view should be only big enough to enclose its content (plus padding).
