What is the difference between MaxPool and MaxPooling layers in Keras?

They are the same... You can test it on your own

import numpy as np
import tensorflow as tf
from tensorflow.keras.layers import *

# create dummy data
X = np.random.uniform(0,1, (32,5,3)).astype(np.float32)

pool1 = MaxPool1D()(X)
pool2 = MaxPooling1D()(X)

tf.reduce_all(pool1 == pool2) # True

I used 1D max-pooling but the same is valid for all the pooling operations (2D, 3D, avg, global pooling)

They are basically the same thing (i.e. aliases of each other). For future readers who might want to know how this could be determined: go to the documentation page of the layer (you can use the list here) and click on "View aliases". This is then accompanied by a blue plus sign (+).

For example, if you go to MaxPool2D documentation and do this, you will find MaxPooling2D in the list of aliases of this layer as follow: