even though = 虽然事实如此
even if = 即使假设如此

① even though：事实已经发生/是真的

even though = 虽然、尽管

Even though it was raining, we went outside.
虽然当时确实在下雨，我们还是出去了。

这里“下雨”是一个事实。

再比如：

Even though he was tired, he kept working.
虽然他确实很累，但他继续工作。

② even if：假设情况

even if = 即使、哪怕

Even if it rains tomorrow, we will go outside.
即使明天下雨，我们也会出去。

这里明天还不知道是否下雨，只是做一个假设。

再比如：

Even if he is tired, he will keep working.
即使他累了，他也会继续工作。

我们不知道他到时候是不是累。

⭐ 最容易理解的一组对比

Even though he is rich, he doesn't drive an expensive car.
虽然他确实很有钱，但他不开昂贵的车。

vs.

Even if he becomes rich, he won't drive an expensive car.
即使他以后变得有钱，他也不会开昂贵的车。

所以：

一个简单记忆方法

看到 though：

though = 虽然已经是这样了

看到 if：

if = 如果是这样的话

所以：

even though → 即使事实已经如此
even if → 即使假设如此

另外，even though 和 although 基本可以互换；而 even if 不能随便替换 even though。