The direct influence of an El Niño on land temperatures via the troposphere is primarily a tropical phenomenon, but there are also global effects.
Any large warming in the atmosphere creates different types of waves. Some would be familiar to us and are similar to ocean waves, others have planetary scale wavelengths and are able to create large regions of high and low pressure (Rossby waves). These waves are able to travel out of the tropics and influence the weather in the mid-latitudes, in this way a tropical El Niño event can have a global influence.
In contrast to the tropospheric temperature mechanism of warming, the effect of these planetary waves can differ dramatically from region to region, and their influence on surface temperatures can be by heat transport, or changes in cloudiness or rainfall. A common theme though is the increased sensitivity of land surfaces to leads to larger temperature changes.