*(CATEGORIES[int(prediction[0][0])])* giving me different result for single image prediction from saved model

From a saved model, I am trying to predict a single image. I followed this code - https://www.youtube.com/watch?v=A4K6D_gx2Iw

I am getting different result for two different command-

*model.predict_classes([prepare('tb2.JPG')])*


and

prediction = model.predict([prepare('tb2.JPG')])
*(CATEGORIES[int(prediction[0][0])])*


My saved model have 2 classes, I have used sigmoid activation function for dense layer, and loss function is 'categorical_crossentropy' The code is -

CATEGORIES = ["ba",  "to"]

def prepare(filepath):
IMG_SIZE = 150  # 50 in txt-based