AES Encryption in Java porting to Python

DISCLAIMER: This is INSECURE encryption that I've inherited and everyone involved knows that. What I'm trying to do here is a first step in getting off this legacy system that has even bigger problems that this.

I have an existing system in Java that I am attempting to port to Python that performs an AES encryption as such:

public static String encrypt(String text, SecretKey secretKey) throws Exception {
    byte[] cipherText = null;
    String encryptedString = null;

    // get an RSA cipher object and print the provider
    Cipher cipher = Cipher.getInstance(SYMMETRIC_KEY_ALGORITHM); // AES

    // encrypt the plain text using the public key
    cipher.init(Cipher.ENCRYPT_MODE, secretKey);
    cipherText = cipher.doFinal(text.getBytes());
    encryptedString = Base64.getEncoder().encodeToString(cipherText);

    return encryptedString;
}

The problem I'm having is trying to get the same combination of AES settings to get the same result using Python and the Cryptography library from:

Python Cryptography

I see lots of examples from the seemingly defunct PyCrypto library which I cannot even get to install on my Windows system much less work.

My latest attempt is like this and I do get encryption but it doesn't match the Java AES output:

from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes

key = b'Some random key '
cipher = Cipher(algorithms.AES(key), modes.GCM(b'000000000000'))
encryptor = cipher.encryptor()
ct = encryptor.update(ENC_MESSAGE)

base64EncodedStr = base64.b64encode(ct).decode('utf-8')
print('BASE64:', base64EncodedStr)

Update based on rzwitserloot's answer.

I changed the mode from GCM to ECB and the result I'm now getting in Python is almost the same. First of all here is what the updated code looks like:

key = b'Some random key '

cipher = Cipher(algorithms.AES(key), modes.ECB())
encryptor = cipher.encryptor()
ct = encryptor.update(PLAINTEXT.encode('utf-8'))

base64EncodedStr = base64.b64encode(ct).decode('utf-8')
print('Encrypted:', base64EncodedStr)

The reference (i.e. Java) output is 1004 characters long while the Python output is only 984 characters long. But up to 3 characters from the end of the Python string they match:

I did check with decryption and found that both encrypted text string decrypt to the same plaintext.

FINAL UPDATE:

The padding was the problem. I updated the code to use PKCS7 padding like this and I am now getting the same result from Java and Python:

from cryptography.hazmat.primitives import padding as symmetric_padding

padder = symmetric_padding.PKCS7(algorithms.AES.block_size).padder()
padded_data = padder.update(PLAINTEXT.encode('utf-8')) + padder.finalize()

ct = encryptor.update(padded_data)