How are repeated trials different from replication?

Hint: Repetition is doing multiple trials in your own experiment to get average value.
Replication can be termed as different people doing the same experiment that one has already done using the same tools and following the same procedures, to precise the value more.

Complete step-by-step answer:
Repetition and replication are done in an experiment to get precise measurement. Let us understand their meaning, and also the difference between them with an example
A class has been assigned a task of measuring the average length of trees in a jungle, several groups have been formed in order to complete this task. A member of group $ A $ has measured the length of a tree and noted it, to get an average length, the members of group $ A $ totally measured the length of $ 10 $ trees and took the average length (say $ x $ ).
Now it's turn for group $ B $ and $ C $ members to measure the length, they went into the same jungle and measured the length of different $ 10 $ trees and took their respective average length (say $ y\;{\text{and}}\;z $ respectively). And finally, they all have taken the average of group $ A,\;B\;{\text{and}}\;C $ to get a final average length of tree in the jungle (say $ w $ ).
Group $ A,\;B\;{\text{and}}\;C $ has done repetition individually by measuring length of $ 10 $ trees. And $ B $ replicated $ A $ and $ C $ replicated $ A\;{\text{and}}\;B $ by performing the same experiment with the same tools and samples.
The value of $ w $ will be more precise and accurate in comparison to $ x,\;y\;{\text{and}}\;z $ because $ x,\;y\;{\text{and}}\;z $ are the result of repetition and $ w $ is the result of replication.

Note: Replication and repetition are two important parts of the experiment to get precise measurements. Replication gives more precise and accurate value than repetition because repetition reduces machine error but replication reduces human error too.